In Spain, the ruins of a Roman military camp sit along a flooded section of a river.

A reproduction of the famous prehistoric cave paintings is hidden underground at the National Archaeological Museum.

Famed architect Antoni Gaudi built this generous thank you gift to a friendly host who housed him during a job.

This small and often-overlooked museum holds some of Spain's finest artistic treasures.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

A 16th-century Andalusian palace.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

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.

Its buzzing collection honors vibrator history.

One of the last remnants of the city's Chinese nightclub scene is now a dive bar selling killer mai tais.

This is one of the last remaining theatres in Canada to feature an Art Moderne architectural style.