Museum dedicated to the terror regimes of Hungary.

This off-beat, quirky communism-themed bar isn't afraid to poke fun at its history.

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

Abandoned railway line circling the city of Paris.

Paris' linguistic guide to the international language of, yes, love.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

What looks like a normal building is really a hollow facade hiding a subway vent.

A subterranean shelter remains intact under a busy Paris railway station.

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.