It's unclear what caused the fire that led to this opulent hotel's demise.

The interior of this Serbian royal family's mausoleum is covered with exquisite mosaics.

This memorial park stands on the site of one of the largest mass executions of the Second World War.

An Art Deco Icarus statue adorns this abandoned gem of Yugoslav Modernist architecture.

The world's second-largest sundial, made entirely out of stone.

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

Where royalty waits in the height of luxury.

Designed as a reminder of one of the darkest moments in Austrian history.

Inside the corridors of this flea market, visitors are sure to find some obscure and odd treasures.

A monument to one of Croatia's famous freedom fighters.

Where visitors can play more than 150 retro arcade games.

One of the world's largest amber altarpieces is housed within this reconstructed medieval church.

A marker honors the brief peace found by a tormented artist in the fictional land of Kcymaerxthaere.

Disturbing works of outsider art, carved from whole logs.

The shattered remains of the world's once tallest structure.

The two abandoned overpasses are among the largest bridges in Poland.

This extensive collection covers thousands of years of Polish military history.

The hollow trunk of this 650-year-old tree was used as a hideout by two Jewish brothers during World War II.

In northeastern Poland, the ruins of a massive granary overlook the Narew River.

This fairytale inspired, warped building houses restaurants, shops, and a radio station.

A 90-ton, gravity-defiant steam locomotive shoots for the skies in this bizarrely beautiful public artwork.

This imposing 20th-century castle was abandoned before it was ever completed.

Order “Proletariat’s Cutlet” at this communist-themed restaurant allegedly once visited by Lenin.