Workers prepare for an event to commemorate the restoration of the Main Hall at Union Station. (Matt McClain/The Washington Post)

After decades of being cluttered with obstructions, and after it was significantly damaged in 2011 by a rare earthquake in the nation’s capital, the soaring Main Hall of Union Station has been restored to the grandeur that train travelers in Washington first marveled at 109 years ago.

Enter through the front doors of the cavernous, Beaux-Arts-style rail station, look around, then straight up, and the view of the immense “General Waiting Room,” as it used to be called, is now much like it was in 1907, when renowned architect Daniel Burnham completed a masterwork befitting a city of monuments.

Minus the spittoons today, of course.

“It is a place that has seen a lot of change,” Deputy Transportation Secretary Victor Mendez said Thursday night at a ceremony in the Main Hall marking the official end of a five-year, $20 million restoration project.

“It still stands as a proud icon of the capital’s landscape,” he said. “When it was built, it not only connected two rail systems” — the Pennsylvania Railroad and the Baltimore and Ohio Railroad (thus “Union” Station) — “but it also allowed for the creation of the Mall and helped spur the city’s expansion.”

With a 26,000-square-foot floor of Greek Pentelic marble and a coffered ceiling more than 90 feet high, detailed in a gold leaf, the Main Hall “was once, believe it or not, the largest room in the world,” Stephanie Meeks, president of the National Trust for Historic Preservation, told the gathering.

Plenty of photos were on display of the Main Hall as it looked when Teddy Roosevelt was in the White House: a Western Union telegraph desk along a wall, men in derbies, their wives swaddled in ankle-length dresses, holding valises and waiting for steam locomotives, no Amtrak or MARC or VRE commuters in sight.

In those days, there were rows of polished mahogany benches, gone now except for one bench on exhibit, surrounded by velvet ropes.

“At some points it can seem like it’s really rushed in here,” Mendez said. “But there are other times when it’s important for us to slow down and really admire what we have.”

As decades passed, though, the stately room seemed to be taken for granted.

During World War II, with many more thousands of travelers arriving in Washington than ever before, extra ticket counters were hastily put up in the grand space. In the 1970s, after airliners had become the nation’s principal mode of long-distance travel, the Main Hall was used as the site of a bicentennial visitors center.

In the mid-1980s, the aged station was closed for a few years for $160 million in renovations. And in more recent times, there were souvenir kiosks, enormous planters and a restaurant in the middle of architect Burnham’s classic expanse.

Then, on Aug 23, 2011, an earthquake rattled the East Coast, including Washington, and damaged the hall’s towering, barrel-vaulted ceiling.

That led to the renovation, a joint project of the National Trust for Historic Preservation, the Ashkenazy Acquisition Corporation and the Union Station Redevelopment Corporation, with contributions from American Express.

The “historic plaster ceiling,” reinforced with “seismically sound” steel framing, has been repainted and detailed with 120,000 sheets of 23-karat gold leafing, the group said. The ancient marble floor is still in place, chipped and stained here and there, but new marble is on order from a distributor in Greece.

The heating and air-conditioning systems, a non-1907 concession to modern convenience, have been upgraded. And gone are the many obstructions.

“I could stand here all night and talk about how preservation ennobles us, how it attracts tourists, how it spurs economic growth and can help address the problems of our cities,” Meeks said, her voice echoing in the vast hall. “But you need only walk into a space like this restored Main Hall to know that our lives are better when our buildings are protected.”