This mysterious, medieval cathedral remains unbuilt but fiercely protected.

This exquisite, alienesque piece of Soviet architecture is being threatened by modern shopping malls.

A mysterious carving from 17th-century London seemingly depicts a young boy sitting on a bread basket.

Two gilded cherubs perched on a church bell tower have been reminding visitors of the finitude of life since 1760.

The largest of Denmark's seven mysterious round churches stands on an island in the Baltic Sea.

The first (but not only) upside-down house in Germany.

These ornate arches show how the course of the River Thames has changed.

This building’s ghostly exterior reflects its former lives as a prison, school, and funeral home.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

These coffin-like Brutalist balconies were inspired by a nearby mine.

Skulls and skeletons are omnipresent in this church dedicated to souls trapped in purgatory.

The fences outside some of South London's estates are made from recycled World War II stretchers.

Dublin's most modern, visually spectacular bridge is modeled after Ireland's national emblem.

This medieval manor house was equipped with secret compartments for hiding priests.

A cone-shaped top and cylindrical body set this 900-year-old structure apart from other Italian bell towers.

A fantastical bed and breakfast with magically unique rooms.

This demon atop the Notre-Dame de Paris looks utterly bored.

This fairytale medieval church in Poland originally spent centuries in Norway.

A university observatory dome painted to resemble the beloved 'Star Wars' droid.

This eclectic sanctuary is a hodgepodge of various architectural styles, all crammed into one building.

A mysterious ruin shrouded in more folklore than fact.

An architectural oddity hides in plain sight on this iconic London bridge.

Legend says this demonic carving inside a medieval cathedral was one of Satan's minions.

Fragments of human bones are embedded in the walls of this quaint alley.