The ancient tomb acts as a calendar that keeps perfect time.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

A 13th-century convent where St. Margaret of Hungary spent her teenage years.

"Medieval" castle built in the mid-20th century by one family.

Budapest's Communist-era statues, banished to the suburbs.

Museum dedicated to the terror regimes of Hungary.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

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

This small chapel holds the mummified heart of one of the heroes of the Greek Revolution.

Legend says it was constructed with the destroyed pillar of an ancient Greek Temple.

This historic structure has been used as a mosque, a barracks, a prison, a school, and a bakery.

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.

There are many Byzantine-era churches still standing in Athens, but this is the only one with a 2,500-year-old column rising through its roof.

This architecturally eclectic early-20th century mosque was built as a place of worship for the Islamic followers of a Jewish messiah.

The Greek island's old British cemetery feels like a forgotten garden.

A little-known park with unusual, half-ruined structures and a mystical energy.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

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

An abandoned Byzantine fortress and notorious prison.

This gem is often wrongly overshadowed by the larger, newer Metropolis church in Athens.