Mark Twain was thinking big in 1874 when he moved into his new 19-room mansion in Hartford. Little expense was spared. Following the publication of his best-selling novel Tom Sawyer in 1881, he had Louis Comfort Tiffany “do” the interior.

It seemed fitting that Mr. Twain wrote The Gilded Age there, and had to leave in 1894 because he was close to broke. Bad investments and bank panics had destroyed his fortune. Gilded Ages can end that way.

Fast-forward to 2009, when Americans are trying to recover from another era of overreach. The Mark Twain House has been a tourist site for over 40 years, but again faces bankruptcy, but not because of the cost of the house, whose restoration had been painfully funded over the decades. The current threat is an Education and Visitors Center next to the house, a 35,000-square-foot, $16.3 million facility that opened in 2003 to great critical acclaim. Unfortunately, the funds never materialized to pay for it.

The museum stands as a landmark to the grandiosity that overtook many cultural institutions during this most recent Gilded Age. A leveling off of admissions to the Mark Twain House at about 53,000 a year was deemed a crisis meriting an enormous building program. The increase in attendance since the visitors’ center opening to an annual 68,000 can hardly justify the cost that now jeopardizes the house’s future. It has already forced the layoff of 30 museum employees.

Equally foolish but bigger and uglier is the new Capitol Visitors Center, at the U.S. Capitol in Washington. Born of security concerns following the 1998 shooting deaths of two police officers near the Capitol’s public entrance — and the need for a more comfortable waiting place for tourists — the Visitors Center ballooned into a 580,000-square-foot monstrosity. Not surprisingly, the original construction budget of $265 million doubled to $621 million.

Architecture critics have panned the design. Philip Kennicott, of The Washington Post, termed it “slick pomposity.” The vast spaces are cold and reminiscent of airport waiting areas and shopping malls. The center’s architect, the international firm RTKL, has done lots of shopping malls.

The interior contains a bizarre collection of statues of great Americans (for example, Hawaiian King Kamehameha I and Apollo 13 astronaut John Swigert) and of a great idea (The Statue of Freedom, which takes a female form).

Like ambitious museum interpretation centers everywhere, this one comes equipped with the usual interactive touch screens. There’s also a Wall of Aspirations, which Mr. Kennicott calls a “kitschy tic” from the exhibit’s designer, New York-based Applebaum Associates.

And so we have this monstrous new Capitol Visitors Center weighing in at over half a million square feet, and it cost only $356 million more than planned. Mistakes were made, but all would not seem lost.

Unlike the foundation-financed Mark Twain House museum, cost overruns here can be picked up by the U.S. taxpayer. And, as the architects promised, the center was largely built underground so as not to disturb the 1874 landscaping of Frederick Law Olmsted, a masterpiece in itself.

But no such luck on that last reassurance. As Mr. Kennicott points out, there’s no such thing as a truly underground facility. One needs entrances and other features. The beauty of the Capitol’s East face has been “demolished,” he says, by the intrusion of a bridge over a moat-like entry. Structures housing elevators for handicapped visitors, meanwhile, look like guard towers.

Hundreds of trees were ripped up or moved in the construction, including many of historical significance. And for what?

A silver lining in the recent Gilded Age’s ongoing collapse should be a slowdown in the building of inflated showplaces to accompany national treasures. We appreciate that ours is the age of computerized special effects and a glitz deficit could lead to smaller attendance figures. If that happens, so be it. Not everything can be measured in numbers.