World's largest bell sits on the grounds of the Kremlin in Moscow.

The avant-garde design was able to bypass strict Soviet regulations on architecture.

A sculpture park of the tossed aside relics of the USSR, from Stalin to a massive Soviet emblem.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

Moscow's imposing monument to the Space Age.

This newly renovated Soviet-era outdoor exhibition center is bigger than the principality of Monaco.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

The prototype for all Nazi concentration camps.

An early work of the architect Álvaro Siza Vieira, these swimming pools blend into the beach.

The world's first ice hotel is still one of the most elaborate and beautiful.

Legend has it this fountain built to symbolize the Pope’s power hides a strange secret concerning Neptune's manliness.

One of the world's tallest statues is also one of its most hated.

In the world's oldest university is a stunning 17th century anatomical theater carved from spruce.

Over 100 towers were built in Bologna during the Middle Ages, but only 22 survive.

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

Spain's stunning solar energy plant.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

An eerie collection of the surviving structures from a past celebration of the future.

This abandoned naval battery stood at the ready as recently as the 1980s.

A cluster of granite granaries perched on stilts.

A small window on Via Piella offers a lovely and rare peek at Bologna's lost canals.

Macabre astrological automaton clock dating to the late 1400s.

Europe's largest collection of matchbox designs is a fascinating exploration of the cultural history of the world.