A 19th-century fortress and collection of artifacts offer a tour of Saudi history.

For centuries, Jeddah’s old town was a major trading port and a point of entry for Hajj pilgrims traveling by sea.

An unfinished tomb carved into a giant boulder in the Arabian Desert.

The rocks around this mountain are filled with so many carvings that the area became known as the "open library."

This lonely minaret with an unusual decorative symbol is all that remains of a historic Ottoman mosque.

A museum dedicated to the former country.

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

This striking, historic hotel has major Wes Anderson movie energy.

This small bronze pyramid marks the center of Belgrade, but some say it is a Masonic symbol.

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

A pair of connected skyscrapers form this symbolic gateway.

Different sections of the Zemun Fortress were built in the 14th and 15th century as a response to the advance of the Ottoman Empire.

Walk down these stairs to get an underwater view of Switzerland's Lake Zug.

Remains of the walls of the Roman city named for its founder

A monument at Alicante Marina honors a little-known hero of the Spanish Civil War.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

A comprehensive look at the art of Joaquín Sorolla in his former home in Madrid.

Stunning Roman aqueduct used for 1900 years and still standing.

You can soak in private hot tubs infused with beer while pouring unlimited Czech beer from your own tap.

The only monument to name all of the passengers and crew who died on the RMS Titanic.

The modern birthplace of Irish freedom.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The comedy and tragedy of Oscar Wilde is preserved in a Dublin park, captured in a sculpture of colorful stone.