The world's largest key collection features keys to the White House, Frankenstein's castle, and Hitler's bunker.

Modern technology and live displays tell the story of the Pacific during WWII for the Internet generation.

Controversially claiming the title of world's biggest bass drum, UT's Big Bertha was once made radioactive by the Manhattan Project.

150 or so scrounged-up lamps, chandeliers, and lanterns light up this alley in central Athens.

This church combines Christian, Byzantine, and ancient Greek architectural elements.

An islet filled with wooden houses where the open sea meets a lagoon.

Get hands on with the technological marvels of the Classical world.

This small museum once served as a royal hunting pavilion for King Otto Friedrich Ludwig.

One of the greatest collections of coins in the world is housed in the former mansion of an archeological pioneer.

A preserved portion of an ancient Athens barrier is displayed in a hotel basement.

This little Greek plateau is home to thousands of rustic, white-sailed windmills.

The oldest standing Byzantine church in Athens is tucked within a monastery in the middle of an upscale shopping district.

Ruins of a 13th-century fortress perched above a breathtaking Mediterranean bay.

This medieval "painted village" is famous for its geometric facades.

An abandoned Byzantine fortress and notorious prison.

This town named for the ancient God of War is home to fewer than a thousand people, but it's the birthplace of the Greek Revolution.

Temple complex that once housed the famous statue of Nike.

The ruined doorway is a portal to the building's turbulent and torturous past.

The ruins of this monumental city founded by the first Roman Emperor are strangely overlooked by most travelers.

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

Large collection from the 3rd millennium BCE.

Local lore says two enemy dragons live within these breathtaking mountain lakes.

An autonomous republic of Orthodox monks.

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.