The old observatory in Copenhagen has a spiral corridor used as a racetrack.

These slanted cubic abodes are a creative if odd solution to a zoning pickle.

A celebrated bandstand at the center of what was once the worst slum in London.

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

Strange secondhand shop showcasing taxidermy and oddies

Overlooking the burial ground is a tower designed to prevent thieves from snatching the recently deceased.

This otherwise ordinary close on the Royal Mile constituted the end of the world for Edinburgh’s poorest residents.

A labyrinthine network of chambers with a storied past hides below Edinburgh's South Bridge.

Giant eggs, walls of bread, and nightmare surreality mark the largest collection of works by Salvador Dalí.

A public urinal so pretty, it was declared a national monument.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

A temple to modernity, tucked away amid Barcelona's more well known museums.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.

London's old-school healing garden.

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

A famous burial ground with a history both grim and literary.

A makeshift shrine to the late rock star is still kept up on the nondescript façade outside 1 Logan Place.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

Pre-Nazi swastikas adorn the sculpted pachyderms flanking this brewhouse portal.

This chimerical bridge/tunnel appears to dead end right into the sea.

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.