This plaque marks the former home of one of the first women physicians in the Netherlands.

A hidden church in a hidden courtyard tells the story of the Miracle of Amsterdam.

A set of seven houses, each built in a style that represents a European country.

This massive mural by famed pop-artist Keith Haring was hidden for almost 30 years until its 2018 rediscovery.

Amsterdam's former hotspot for public executions and dissections.

Tucked in the back of a flower shop, its collection details the fascinating history of the Netherlands's iconic symbol.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

This unusual elevator doesn’t stop or slow down.

This cheese shop also houses a museum devoted to Dutch dairy.

This historic Amsterdam bar used to accept sailor's monkeys as payment.

The world's only museum devoted to the wonders of fluorescence.

This statue of a falling man commemorates a teenage martyr of the Hungarian Revolution.

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

An old spa town in the mountains of Romania where, according to legend, the great hero Hercules once bathed.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

One of the oldest churches in Romania is believed to have been built on the site of a pagan temple.

A countryside Romanian cemetery filled with colorful crosses bearing lyrical, ironic, or satirical rhymes.

The legendary cliffside castle of three-time Voivode of Wallachia, Vlad the Impaler.

This solitary monastery may hold the remains of Vlad the Impaler (but probably not).

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

Some call this eerie forest of crooked trees the "Bermuda Triangle of Romania."

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.