This Cape Cod museum exhibits what it claims is the only authenticated pirate treasure in the world.

America's smallest national park site is the former residence of exiled Polish national hero Thaddeus Kosciuszko.

This Manhattan museum houses one of the largest collections of Spanish art and manuscripts outside of Spain.

A discreet little stairway on St. Nicholas Avenue leads to a quaint and unexpected cobblestone street of 19th century wooden rowhouses.

The collection is housed in an exquisite mansion that makes you feel like you've been transported to an Italian villa.

This artist's home turned gallery/museum preserves the creator's love of "Eastern" influences.

This hidden sculpture garden full of Wild West art is one of San Antonio's best-kept secrets.

Breathtaking Byzantine paintings cover the inside of this 12th-century church.

Sniff the Titan Arum's rotting flesh.

This little-known Revolutionary War fort is supposedly haunted by the ghosts of its past.

An artist's cute bronze subway sculptures belie his violent artistic past.

A hidden "place of interment for gentlemen."

Obscure Freemasons still live in D.C.’s largest private residence.

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

The oldest bibliophilia club in America, with exhibitions on historic books and graphic arts.

The institution is sitting on a goldmine of 21,000 paints, varnishes, pigments, and primers preserved for posterity.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

The ceiling of this vintage movie palace is covered in fantastic Art Deco murals.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

Hordes of precariously balanced stone figures crowd the shores of the Hudson River.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

The largest library in Latin America owes its existence to an Old World earthquake and a Napoleonic invasion.

Western Europe's only representation of a Roman goddess still in its original location sits in an unassuming park.

A minotaur, a labyrinth, and a dubious restoration pull in visitors from around the world.