Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

Roman ruins top white travertine terraces formed by ancient hot springs.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

This equestrian statue of Constantine the Great has been the subject of criticism for centuries.

The Vatican's secret porn-festooned bathroom was painted in erotic murals by one of the greatest artists of the Renaissance.

Breathtaking and huge 430 year old maps of Italy.

Artworks by loners, prisoners and the criminally insane.

There are hidden patterns on the subway seats of some Stockholm metro cars.

This pair of unsuspecting buildings are in fact the very first modern skyscrapers in Europe.

Stockholm's narrowest alley is barely over two feet wide.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

Stockholm's deepest subway station is also a stunning ecological wonder.

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

This millstone commemorates a gruesome tale that may have been the source of the city's name.

This poignant sculpture of a gnarled weapon is a symbol of non-violence.

Swedish skyscraper with a 90° twist.

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

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

A lush indoor jungle fills this bustling Madrid transportation hub.

An ancient Egyptian temple in the middle of Madrid, Spain.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

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