This historic hotel invented the chocolate brownie.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

The neighborhood church casts a breast-shaped shadow that locals have come to call the “two o’clock titty.”

The key to turning shifting dunes into the green oasis of Golden Gate Park.

Early prototype for Frank Lloyd Wright's Guggenheim.

This private residence was the template for one of the most beloved television homes of all time.

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

Plaques on its facade commemorate the Tiber's most destructive deluges.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

2300-year-old Roman road connecting the empire.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

A typical "Old South" manor, once owned by author Anne Rice, served as the setting for several of her witchcraft sagas.

After the oysters have been shucked, and the restaurant's been shuttered, the terrazzo sidewalk from the 1940s is all that remains.

This quaint museum in a long-running workshop is dedicated to a fixture in New Orleans lighting.

This cathedral dedicated to Louis IX, sainted King of France, holds many secrets.

This distinctive Crescent City tradition dates back to the days of horse-drawn carriages.

The beautiful, fruit-covered facade hints at this building's former life.

The oldest operational cathedral in the U.S. has one shell of a way of projecting speakers' voices.

A small park on Bourbon Street features life-size bronze statues of New Orleans musicians.