According to author Dan Brown, the Capitol is a building that holds secrets few people even know exist. From a “killer bathtub— to a hole in the Rotunda, Brown claims there is far more than meets the eye in this historic building.

In Brown’s latest novel, “The Lost Symbol,— readers follow “symbologist— Robert Langdon as he embarks on a treasure hunt — much of which occurs in the Capitol — in Washington, D.C..

So just how much of this thriller, which sold a whopping 1 million copies in its first day, is real? We went to Senate Historian Don Ritchie for answers.

The book is “sort of a little bit like ‘National Treasure’ was for the National Archives; it brought a lot of people in, but the Archives had to spend a lot of time telling people there was no map on the back of the Declaration of Independence,— Ritchie says, referring to the 2004 movie.

Early in the book Brown writes that the Capitol is “a treasure trove of bizarre arcana.— For instance, there was the “killer bathtub responsible for the pneumonic murder of Vice President Henry Wilson.— According to Ritchie, the bathtub plays a role, but Brown’s version really only provides a small part of the story.

Wilson “apparently suffered a stroke or some major illness while he was bathing and he was brought upstairs to the vice president’s office and he died there,— Ritchie says.

But bathtubs in the Capitol? Apparently the venerable building was outfitted with bathtubs because in the 1800s many Members of Congress lived in Capitol Hill boardinghouses with very primitive plumbing. Bathtubs were installed on both sides of the Capitol. In fact, there was also a barber shop and a masseuse.

“You could go and soak in the tub, get your beard trimmed and get a rubdown before you went upstairs to legislate,— Ritchie says.

In the 1890s, when the Capitol was being wired for electricity, the bathing rooms were turned into electrical rooms. Today, though, one tub is still visible in the basement of the building.

In “The Lost Symbol— Brown also claims there is “a staircase with a permanent bloodstain over which an inordinate number of guests seem to trip.— While a murder did occur on the steps leading up to the House chamber, it is unclear whether there is actually a bloodstain.

In 1890, former Rep. William Preston Taulbee (D-Ky.) got into a scuffle with journalist Charles Kincaid, who had written a story that ended Taulbee’s political career. During the scuffle, Kincaid pulled a gun and shot Taulbee dead on the stairs. Today there is a mark on these steps.

“The curators insist that it’s a flaw in the marble that has become visible as people have gone up and down— the stairs, Ritchie says. “But it happens to be in the spot where the shooting occurred. I often tell people they can decide on their own if it’s blood.—

Ritchie adds that for years reporters in the House Gallery had a “Kincaid Society— in homage to the reporter. “I imagine others had fantasies— of doing the same thing, he says.

Much of the novel takes place in a secret basement in the Capitol called the “SBB— that acts as a private storage space. In reality, there are many hidden corners in the Capitol, though none that sound quite as titillating and mysterious as the SBB.

“There’s a lot of space down there, some of which you can get to, some of which you can’t,— Ritchie says. For example, when construction began on the Capitol Visitor Center, a storage room was discovered under the main stairs that lead to the Rotunda. The room contained historical records.

The book also talks of a large hole that was once in the center of the Rotunda floor and that led to the crypt. This much of the story is, in fact, true. When the Capitol was built, it was initially thought that George Washington would be buried in this crypt. Visitors to the building would be able to look down on his casket through this hole. In the end, Washington’s family asked that his body remain at his beloved Mount Vernon, a request that pleased the opposing party, which had recently taken the majority. The hole was closed in the 1820s.

“The opening in the center of the Rotunda was eventually closed in part because the humidity was doing damage to the artwork,— Ritchie says. “It was damp and they didn’t have good heating and all the rest, so it proved to be a detriment.—

While many of the mysteries of the Capitol are embellished in this new book, Ritchie says he is hoping “The Lost Symbol— will convince people to see the building for themselves.

“Now at least we do have the new Capitol Visitor Center, which in addition to housing people coming in to take the tours has a very large exhibit on the history of the Capitol,— he says. “So when people are curious about it, they can actually go in and see what Capitol Hill looked like at the time.—