An enormous, inside-out glass globe built in 1935.

Built for an exposition in 1915, these horticultural displays have stood the test of time.

This enormous censer uses a pulley system installed over 400 years ago.

This former charity hospital for elderly clergy houses some of Seville’s most treasured paintings.

This Roman arena once played host to bloody gladiatorial battles.

Long tunnels run under the ancient chariot racing circuit to the tower.

Stunning Roman aqueduct used for 1900 years and still standing.

The fragmented remains of a massive public bath connected to the city's water supply.

Once the grandest synagogue in medieval Spain, it now stands as a memorial of the 15th-century Jewish exile.

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

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

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

Giant topiary dog once played a role in a terrorist bomb plot.

This 6th-century church has the largest and best-preserved collection of Byzantine mosaics outside Constantinople.

Ancient snack bar of the Roman Empire re-opened.

Water and windows define this defensive Italian well.

This strange bovine gargoyle is said to have been put in as a passive aggressive form of revenge.

Renaissance hospital featuring a rotating door into which unwanted babies were dropped.

The graveyard is filled with beautiful funerary art and boasts breathtaking views of Florence.

This 1st-century CE Roman bath sits under a carpark.

The Emperor Tiberius' palace of debauchery.

This clifftop arch is a natural stunner.

Was this cave created by Hercules's wrath, the devil, or volcanic activity?