A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

27-room home built with the fortune of a sugar magnate.

One of few lasting examples of the brief octagon craze that developed into folly.

A brooding mansion of clinker brick stands out among the Victorian houses of Pacific Heights.

Built in 1906, this unique building was the first Hindu temple in the United States.

The only urban monument in the world designed by the great surrealist painter Salvador Dalí.

This 18th-century sundial was designed to calculate the date of Easter each year.

Legend says this sacred tree was a gift from goddess Athena.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

An ancient octagonal weather station named for the eight Greek gods of wind.

In this Parisian garden's grotesque former life as a zoo it fed exotic animals to the bourgeois and put humans on exhibit.

Ancient barriers wrap around what was once an important stop along the Silk Road.

Monasteries on rock pillars, once accessible only by frayed ropes.

A rare example of a medieval house in Rome adorned with a melancholic inscription.

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

This Parisian gem is one of the most incredible ethnographic museums in the world.

The former headquarters of history's oldest megacorporation.

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

A brutalist gem towering over the heart of Milan.

The pile of books behind the dignified writer gave the statue a most undignified nickname.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.