These crumbling Latvian forts make for some haunting seaside ruins.

3,000 market stands in five former Zeppelin hangars.

A hidden bas-relief of a hare on a church main portal that brings good luck to the ones who find it.

Two awe-inspiring globes from the reign of the Sun King hang from the ceiling of France's national library.

This Parisian fountain is a little bit fantasy and a little bit nightclub.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

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

High Victorian fantasy created a fairytale castle out of a ruined fortress in Wales.

A rocky sea serpent hides caves, blowholes, and a spectacular natural bridge.

A subterranean playground in an abandoned slate mine.

A holy well supposedly infused with a saint's spirit flows within this quaint chapel.

Gilded heaven for philatelists and architecture freaks, still in full working order despite sitting atop tremulous ground.

Twelve natural mummies are displayed in the crypt of this former monastery school.

High atop a Mexican rainforest mountain, this ancient pyramid once drew pilgrims countries away.

Every equinox this Maya pyramid puts on a spooky ancient light show.

An island filled with hundreds of hanging, decomposing, decapitated dolls.

A vibrant street away from the typical tourist track, lined with colorful, mosaic-covered houses.

This stone obelisk is a relic of the 17th-century Swedish mile markers.

A miniature model of the iconic Stockholm department store.

Sweden's oldest animated sign is still lighting up the skyline today.

This grisly exhibit houses skeletons and weapons from a devastating 14th-century clash.

The remains of Alfred Nobel's first nitroglycerine factory can still be found on the shores of a Swedish bay.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

The world's oldest bookshop still in operation.