The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

An empty relic of the Moscow Olympics crumbles away in Estonia's capital.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A whimsical bridge adorned with decorative dragons.

Moscow's imposing monument to the Space Age.

Museum celebrating the achievements of the Soviet space program.

The design of the Palacio Salvo has been described as "a lighthouse on top of a building."

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

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

Taxidermy of the racing horse with a huge heart, who inspired hope in the Depression.

Macabre astrological automaton clock dating to the late 1400s.

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

Go surfing on this urban wave, "hacked" by local surfers.

Giant marble phalluses on the sacred island of antiquity.

The only surviving prototype for Buckminster Fuller's house of the future.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

Holy Hindu shrine in an enormous, monkey-filled limestone cavern.

A church of bones, decorated with 40,000 human skeletons.

A marvel of Byzantine engineering under the streets of Istanbul.

Ancient serpentine sacrifice holder that has stood the test of time.

The "Prussian Versailles" that is as glorious today as when it was built.

A sharp bend in a dramatic river canyon cut through red rocks.

105-foot wide giant metallic flower blooms anew every day in the heart of Buenos Aires.

This giant dish located in a sheep paddock was the primary receiver of Apollo 11 TV transmissions.