A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

These caves secretly held national treasures during World War II.

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

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

The oldest cemetery of modern-day Athens blends the modern and ancient worlds.

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

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Vienna's diversity-themed traffic lights were inspired by the Eurovision Song Contest.

A rooftop restaurant hides in plain sight atop Vienna's Palace of Justice.

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

The beautiful baroque library of the Hapsburg empire.

The final resting place for the remains of 143 Habsburg royalty.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

An industrial site turned into Hungary's most cherished natural wonder.

A random tree outside a Budapest hotel has become a DIY shrine to the late singer.

Some of the greatest minds in the history of Hungarian art and science converged in this café.

A two-way chairlift system between Zugliget and the highest point in the city.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

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

This bar and museum are devoted to the controversial comic book work of Kája Saudek.

This charming wooden church was disassembled and moved not once but twice before settling in this Prague garden.

This doorless 20th-century elevator doesn't stop or slow down.

The hidden lair of an alchemist rediscovered in a 2002 flood.