Numerical symbolism abound at East Asia's oldest observatory.

A beautiful opera house in the heart of Amazonia has recently restarted performances after a 90-year hiatus.

This striking, two-toned confluence of rivers is visible from space.

The pedestrian traffic signals in Brazil's teeming metropolis light up with clues to nearby landmarks.

The crypts are so large they're basically their own underground church.

A faux desert landscape in the middle of the jungle that sprouts oases during the rainy season.

As one of the world's largest hydroelectric dams this plant took two countries to get built.

A series of waterfalls so massive they straddle the border of Argentina and Brazil.

These spectacular ruins were built by Spanish padres in the 17th century.

A wooden dock art installation on Chiloé Island taps into the island's indigenous mythology.

The largest geyser field in the southern hemisphere is a spectacular sight.

The world's largest wooden structure.

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

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

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

The beautiful, ornate weather station is the most popular geocache in Salzburg.

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

The prototype for all Nazi concentration camps.