On the evening of August 17, 1964, the caretaker locked up the Forestry Building in Portland, Oregon, at about five o’clock and went home. Within forty-five minutes, neighbors could see that something was wrong. By the time the first fire crews arrived at roughly a quarter to six, the whole building was burning, and there was nothing they could do to save it. Everything about the structure that had made it famous now worked against it—some two hundred logs with their bark still on, nearly sixty years dry, wooden balconies, wooden stairs, a roof of shakes and shingles, and a nave forty-eight feet high for the air to move through.

Witnesses described flames almost ten stories tall. People came from all over Portland to watch, and the Oregonian reported that some of them were in tears. Windows blew out in the big Montgomery Ward building nearby, and ash came down as much as a mile away. Nothing was saved from the inside.

The cause turned out to be the building’s electrical wiring, wiring that dated back to the year the hall was built. Had the fire started an hour earlier, the caretaker might have caught it in time to raise the alarm. The building that burned that night had stood for fifty-nine years. It had been, by the reckoning of most who saw it, the largest log cabin in the world—a hall 206 feet long, 102 feet wide, and 72 feet high, its great room supported by more than fifty whole Douglas fir trunks, each about six feet thick, set up on end with the bark still on them.

When Oregon later looked at what it would take to replace those logs, it came to an uncomfortable answer: the trees that had built the hall no longer existed in any form that could be matched. How did Americans build a two-hundred-foot log cabin out of whole trees? And why could no one build it today? The answer lies in the fair’s official guide, in the newspapers of 1904, and in the city’s own photographs of the work.

In the spring of 1905, Portland was getting ready to host the Lewis and Clark Centennial Exposition, marking one hundred years since the expedition had reached the mouth of the Columbia River and the Pacific. The city wanted visitors from the East to leave with one idea fixed in their heads: this was the place the timber was coming from. That was not a boast. It was a forecast.

For most of the century before, America’s lumber had come from the pinewoods of Maine, then Michigan, Wisconsin, and Minnesota. By the turn of the century, the best of those forests had been logged over, and the industry was moving west, and moving fast. In 1900, Frederick Weyerhaeuser bought 900,000 acres of Northwest timberland from the Northern Pacific Railroad in a single deal. By 1905, Washington ranked first in the nation in lumber, and Oregon was about to take second.

Between 1900 and 1910, the Northwest’s share of all the lumber cut in the United States rose from eight percent to twenty percent. What the Northwest had was the Douglas fir. It grew two hundred feet tall and more, with a trunk that could run six or eight feet across at the base and stay nearly that thick for a long way up. Easterners had read about trees like that.

Very few had stood next to one. So the fair would show them, not with a photograph, but with a building made of the trees themselves. Even the ground the fair stood on had to be made first. The site the city chose at Guild’s Lake in northwest Portland was roughly 400 acres—180 of them pasture, 220 of them waist-deep stagnant water.

The grounds were planned by the Olmsted brothers, the family firm of Central Park’s designer Frederick Law Olmsted, for a fee of $5,000. Over two years, crews filled the slough, built terraces and promenades, and laid out exhibition halls around an artificial lake. Almost every one of those halls was temporary, built to look grand for one summer and to come down when the fair was over. One building was meant to be the opposite.

On a rise at the top of the grounds, the state of Oregon put up a hall made of nothing but its own forest. The man who found the trees was a logger. Simon Benson was born Seaman Bergerson in Norway in 1851, spent eleven years in Wisconsin, and came to Oregon in 1879 with almost nothing. He worked in logging camps and sawmills, then started logging on his own along the lower Columbia River.

What made Benson rich was a change of method. He was one of the operators who took the oxen out of the woods. In their place he put compact steam donkeys—engines that winched a felled log in on a wire rope—and short logging railroads that carried the logs down to the water. He wrote later that steam cut his logging costs by more than half.

It had cost him $4. 50 to log a thousand board feet; with steam, it cost $2. 15. Steam also changed the calendar.

Oxen bogged down in the winter mud of the Northwest, and a logging season used to end when the rains came. A steam winch sat in one place and pulled, mud or no mud, so the logging could go on through the wet months. Across the region, companies pushed dozens of short railroads up small valleys to reach timber that oxen never could. By the time of the fair, Benson held about 46,000 acres of timber, much of it in Columbia County on the Oregon side of the river.

In 1903, his crews started a new logging railroad out of the town of Clatskanie, and in 1904 it brought out its first load of logs. That same year, Benson went into his own forest and picked the trees for the building. Most of the giant logs came from his holdings, and he paid for them. He did not pick them the way a logger usually picks a tree.

A logging crew in 1904 judged a tree by the lumber inside it—height, soundness, the length of clear trunk below the first branches. What the outside looked like did not matter at all, because the outside was going to the mill to be sawed off. For this building, the outside was the whole point. The columns would stand in two long rows down the middle of the hall, and a visitor would walk between them the way you walk down the nave of a church.

So they had to look like a set—roughly the same thickness, roughly the same taper, straight, round, and sound for more than fifty feet. One account describes the columns as hand matched, like a string of pearls. Finding one tree like that was ordinary work. Finding fifty that matched each other was not.

Benson picked them out himself, standing in the forest one tree at a time. Then the trees had to come down. In the Douglas fir woods of that era, felling was done by two men called fallers. The base of an old fir flared out wide and was often full of pitch, so the fallers did not cut there.

They chopped a notch into the trunk several feet up and drove in a springboard—a plank with an iron shoe on the end—then stood on it to work. On the side the tree was meant to fall toward, they chopped a deep wedge called the undercut, mostly with axes. Then they moved to the back of the tree with a crosscut saw, a blade that could run ten or twelve feet long. One man on each end, each pulling in turn, they worked it through until the trunk began to lean and the fallers got off their boards.

A tree of that size was steered all the way down. If it landed across a stump or a rock, a trunk that heavy could break in half. Crews sometimes cleared a bed for it, or built one out of smaller logs, so it would land flat. For this building, the hardest part came after the tree hit the ground.

The bark had to survive. Bark is the first casualty of ordinary logging. A log dragged in by a steam donkey slid across rock, stumps, and other logs, and the bark came off it in sheets. Loggers did not care, because bark was waste.

Here, a scraped log was a ruined log. The logs for the hall had to be handled specially when they were cut and hauled, so that every one of them arrived dressed exactly as it had stood in the forest. The logs that made it out of the woods went to the water. From Benson’s holdings on the lower Columbia, they were floated up the Willamette River to Portland and into Guild’s Lake itself, right to the edge of the fairground.

In December of 1904, the papers reported one of the logs at 27 tons. Another report gave the heaviest of them at 32. The biggest of the foundation logs ran 54 feet long and 5 feet across. Saw into ordinary flooring boards one inch by three, a single log of that class would have stretched for something like thirteen miles.

And there were not a few of them. A Washington paper in June of 1905 gave the total: two miles of logs five and six feet in diameter and fifty-two feet long, together with eight miles of poles and tons of stakes and shingles. Do the division: two miles of logs, fifty-two feet to the piece, is about two hundred logs of that size. All of them old growth.

All of them with the bark on. Then they had to be raised. The surviving accounts do not say exactly how the crews stood the columns up, or who the men were. What they do record is the scale of the problem.

A column weighed as much as a loaded railroad car. It had to go from lying flat on the ground to standing dead vertical in a row at the right height, without being dropped or scraped. In 1904, there was one standard answer to a lift like that. Whatever rig the crew used, it worked on the same principle: a derrick—a tall timber mast held upright by guy lines, a boom swinging off its base, and a wire rope running through heavy iron blocks to a winch.

It was the same tackle that loaded logs onto railroad cars in every camp in Oregon. The rope took the top of the log, the winch took up the slack, and the column came up off the ground one end first until it hung straight and could be walked onto its base. The heaviest logs of all went in at the bottom as the foundation. Overhead, the columns carried the rafters.

Inside, the two rows of trunks held up a two-story cross-shaped center aisle lit from above by skylights. The nave they formed was about forty-eight feet high. Around it, rustic stairways climbed to balconies on the second and third floors, built out of whole logs as well, with big doors opening from those balconies onto porches outside. The outer walls went up the way a settler built a cabin wall, with logs laid lengthwise one on top of another.

The only difference was size. A settler’s wall log was a foot thick, and a man and a horse could move it. These were five feet thick. On top went the eight miles of poles, the stakes, and the shingles and shakes.

The fair’s guide admired its crude facades and its roughly hewn ornament. The front porch was held up by more natural trunks and decorated with pine cones. When it was done, the building had taken around one million board feet of timber. It cost the state of Oregon close to $30,000, and the papers that winter were careful about what to call it.

“The second largest log building ever erected,” one of them said. Most people simply called it the largest log cabin in the world, and nobody at the fair corrected them. Someone could have. A year earlier, a hotel built of logs had opened beside a geyser in Yellowstone—the Old Faithful Inn—which the National Park Service today credits with the title.

They called the Portland building other things, too: the log palace, the timber temple, the log cathedral. That was the whole structure, and every piece of it had grown in a forest down the river. The Forestry Building opened with the fair on June 1, 1905. Close to 40,000 people came through the gates on the first day; admission was fifty cents for an adult and a quarter for a child.

Two trolley lines ran within a block of the entrance, and river steamers carried visitors for ten cents. On the busiest day of the whole summer, more than 85,000 people came. Inside the building, Oregon showed the whole life of a tree. A sawmill ran in one corner, feeding logs to the saws and squaring them, then cutting rough lumber, then finished boards.

Another section showed the making of veneer, doors, window sashes, and wall paneling. A miniature skidding and loading engine driven by electricity pulled tiny logs across a model forest, onto little railroad cars, over a river, and into a log pond at a mill. Machinery makers showed models of the cableways and derricks that were changing logging in the real woods. Because fishing and timber were the two great industries of the Columbia, the state also ran a salmon hatchery inside the building.

Visitors could watch young chinook and steelhead being raised a few feet from the trunks of a virgin forest. There were mounted elk and panthers in natural scenes, and on the walls hung about three hundred photographs of Native Americans by the photographer Edward S. Curtis. The official guide did not hold back.

It called the Forestry Building “the most original architectural creation ever offered to public view. ” The state’s own commission called the forestry exhibit, together with the building, perhaps the greatest exhibit of the entire fair. A later architectural historian put it more simply: it was by far the most popular attraction of the exposition. By the time the fair closed in October, well over a million and a half people had passed through its gates, more than 400,000 of them from outside the Northwest.

Every visitor who walked into that one hall saw more than fifty old growth Douglas firs at once. The fair as a whole brought an estimated $8 million into Portland’s businesses. Then the fair ended, and the temporary city came down. Almost every other hall at Guild’s Lake was demolished or carted away.

Over the next twenty years, the lake itself was filled with rock and gravel, some of it dredged out of the Willamette, and by the middle of the 1920s it was gone. In the Second World War, the ground where the fair had stood held temporary housing for the workers of the Kaiser shipyards. Today it is an industrial district. The city of Portland bought the Forestry Building and kept it, and then for long stretches it did very little with it.

A log building with the bark on is a building that is slowly being eaten. Insects worked into the bark and the wood under it. The whole log balconies warped. In 1914, embers from a fire at the old California building next door landed on the roof, and only quick work by the fire department kept it from catching.

In the 1920s, there was a proposal to take the building down and salvage the logs for lumber. It was turned down, but the state also refused to pay for repairs, and the building was judged a safety hazard and closed to the public. In the late 1940s, sparks from the caretaker’s stove burned a hole roughly fifteen feet across in the roof. By then, the city had to make a decision: fix the building or let it go.

In the 1950s, the Portland Chamber of Commerce raised the money to save it. By then the hall stood on a concrete foundation and served as a forestry museum. The Oregonian described its priceless collection of logging and lumbering exhibits. And by 1959, in time for Oregon’s hundredth year as a state, the restoration was largely complete.

But the people doing that work ran into a question nobody in 1904 had needed to ask. If a column failed, what would you replace it with? They looked into it, and the answer was not encouraging. In 1904, the trees had stood in virgin forest close enough to the rivers to be floated to town.

Fifty years later, the forest that was left lay much deeper in the mountains, and the trees in it were less uniform. A replacement log could no longer be floated to Portland. It would have to come out on a truck, and a log handling system would have to be engineered just to keep the bark from being scarred along the way. Even then, it would have to match the others.

Finding fifty-two matching trees, as one account of that restoration puts it, would have been prohibitively expensive, if not impossible. By then, people were starting to understand what they had—something completely irreplaceable. As one historian of the building puts it, an artifact of a time that was gone and was not coming back. They were right.

They were also out of time. Portland’s civic leaders did raise money to replace the building that burned, but the replacement went up in a different place and in a different way. The Western Forestry Center, designed by the Oregon architect John Storrs, opened in Washington Park on June 5, 1971. It was built to resist fire.

And in the more than sixty years since that fire, nobody has built another hall like the one that burned. What is left is mostly paper. The fair’s official guide. The newspaper clippings with their tonnages and their miles of logs.

The city’s own construction photographs from 1904, with the columns going up and men standing among them. A set of plans in the Oregon Historical Society. There is one more trace, and it is still standing. In 1912, the Great Northern Railway began building the Glacier Park Lodge in Montana, and its owners, Louis Hill and his father, modeled it on the Forestry Building in Portland.

They copied its great hall. The lobby columns are Douglas firs forty feet tall and three to three and a half feet thick, shipped in by rail from the Pacific Northwest because Montana trees rarely grew that large. The timber was cut before the sap rose so the bark would stay on. Those columns still hold up the lobby today.

They are half the thickness of the ones that burned in Portland. And on the street corners of downtown Portland, there are bronze drinking fountains with four bowls still running. People there call them Benson bubblers. Simon Benson paid for them in 1912, reportedly because he was tired of workers showing up drunk on Monday mornings.

Eight years before that, the same man had gone into his own forest and chosen more than fifty trees to stand on end. None of those trees exist anymore. One of them, the papers said in December of 1904, weighed 27 tons.