Hear the quietest sound from across the dome.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

France's most famous cemetery, with some of its most curious tombs.

The celebrated eyesore created by starry-eyed sweethearts.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

The Corinthian columns that towered over Abraham Lincoln’s inauguration stand proud.

Largest Roman Catholic church in North America.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

Bar full of oddities, specimens, artifacts and homages to the great dime museums of the past.

At 207 feet, one of the world's longest continuous escalators.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.