Very few get a first-hand look inside the building's most iconic feature. There is a secret staircase hidden in the Capitol dome, and it goes all the way to the top. Follow Tech Insider ...

Inside, members of ... not to mention an iconic cast-iron dome added to the structure in 1868. Though some travelers express mixed reviews on whether the U.S. Capitol warrants the time and effort ...

The U.S. Capitol dome is really an illusion ... The ribs support the thin, outer shell, but the smaller dome inside can support itself. You won't need as much steel with this double-dome design ...