The oldest standing structure in downtown San Diego.

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.

Tiki luxury on Nob Hill.

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

A 140-year-old castle with underground caves hidden in San Francisco.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.

Books bound in human skin and H. P. Lovecraft's letters are among a few of the treasures this library has to offer.

A 19th century library favored by Edgar Allan Poe and H.P. Lovecraft, known by locals as "the Ath."

Last residence of H.P. Lovecraft featured in his story "The Haunter of the Dark."

You can spend the night as an honorary lighthouse keeper in this quaint, historic beacon.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Macabre astrological automaton clock dating to the late 1400s.

Blitzkrieg bop your way through Berlin's Ramones Museum.

A fascinating insight into daily life in the Eastern Bloc.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

The world's largest piece of copyrighted artwork.

The massive machine creates cracking displays of indoor lightning.

A former waterfront market is now in the center of town due to some interesting Boston engineering.