One of Madrid's oldest trees, with a long and colorful history, resides in El Retiro Park.

A haven for book enthusiasts across the street from Retiro Park.

This effigy of Peter the Great is greatly disproportionate.

Palace where the nearly un-killable Rasputin was murdered.

An 18th century wonder of the world, lost in WWII, re-created at the Catherine Palace.

Gargantuan home of Russian science.

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

Museum celebrating the achievements of the Soviet space program.

Former headquarters of the KGB.

Moscow's other, lesser known kremlin is a fairytale-like cultural complex modeled after Old Russia.

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

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

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

Moscow's imposing monument to the Space Age.

The Cathedral of Salamanca has a number of unusual carvings but none so surprising as a modern astronaut.

The facade of this 16th-century building is decorated with carvings of 300 seashells.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

This influential Renaissance-era library was once the haunt of kings and monks.

According to tradition, King Phillip II supervised construction of the seat of his empire from this seat carved into rock.

This 18th-century pond is one of the main attractions in the Jardín del Príncipe in Aranjuez.

A magnificent, long-abandoned castle built in the wake of the reconquest of Spain.

Guitarist Paco de Lucía overlooks travelers as they pass through this train station dedicated to his legacy.