A stunning architectural yet functional feat, towering over Oslo.

Latvia's symbolic mountain-shaped national library is home to millions of cultural tomes.

The hallucinogenic center of the ancient world.

A Turkish ghost town abandoned in a population exchange with Greece.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

A historic observatory precariously perched at the "Top of Europe."

A marvel of Byzantine engineering under the streets of Istanbul.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

A small museum filled with over 1,000 clocks, and one particular clock calibrated to run until the year 9999.

This abandoned viewing platform has become a monument to unnecessary government spending.

Modern art meets modern convenience in possibly the world's most architecturally important public bathroom.

The once and future home of New Zealand's famed Pink and White Terraces.

The best-preserved ancient theater in the world.

Because sometimes the most efficient route from A to B isn't a straight line.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

This charming woodland trail is peppered with poetry.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

A collection of more than 12,000 shoes, displayed in a building shaped like a shoebox.

A catapult rock from Gotland’s 13th-century civil war is still lodged in Scandinavia's best-preserved medieval city wall.

A modern day curiosity cabinet.

A museum founded to reflect on and remember the human rights abuses under Chilean dictator Augusto Pinochet.

This exceptionally well-preserved ancient marvel also houses a small museum dedicated to Jordanian folk tradition.