One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

One of the oldest seagoing boats in the world can be found at the Dover Museum.

A porcelain company's former dumping ground, completely covered in pieces of collectible ceramics.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

This black sand beach was crafted from volcanic explosions including the historic Minoan eruption.

The ruins of an ancient mansion sits in front of and underneath a contemporary art gallery.

An often overlooked ancient site in downtown Athens with substantial history (and nature).

A Byzantine church containing the holy remnants of three saints sits atop the site of an ancient temple.

These ancient ruins hide in plain sight next to a dessert shop.

Underneath one of the region's most historic roads lies the home of Plato's successor.

This Ottoman-era church is hidden amid a busy tourist area.

The only surviving choragic monument is a trophy awarded in 334 BC for the winning dramatic chorus.

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

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

Where commuters walk through remnants of an ancient Greek necropolis.

This mystical orb covered in strange symbols is thought to have been used in ancient Greek magical rituals.

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

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

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

A Byzantine-era church hidden in a wooded area below the Acropolis.

These caves secretly held national treasures during World War II.

A terrific purveyor of natural history objects and curios.

These historic buildings once housed the headquarters of one of the most infamous gangs of New York.

The artist and New York City icon lived, worked and died in this converted carriage house owned by another iconic artist, Andy Warhol.