Meant to be one of the most extravagant hotels in the world, now an eerie, abandoned architectural gem in Mexico City.

66,000 pieces of art, donated by one of the world's richest men.

Frida Kahlo's childhood home, now a museum of her life and works.

These biodiverse university gardens form a green oasis amid the urban chaos of Mexico City.

A colorful "forest" made entirely from three tons of recycled plastic waste.

Where layer cakes tower above one’s head and there is never a shortage of icing.

Sloth rehabilitation center in the jungle of Costa Rica.

This neon blue river gets its color from a unique mix of bacteria and volcano minerals.

This Costa Rican topiary park is a surreal garden of unearthly delights.

Where dogs like the rare "Fire-Tailed Border Cocker" run free on the mountainside.

The farthest you can be in the contiguous U.S. from a McDonald's location.

This UFO landing strip was created by a charitable Wyoming city that was worried about residents of Jupiter.

Native Americans built this circle of stones, which was used to predict astronomical events.

Charnel house at the foot of Mount Sinai.

The oldest church in the Estonian capital is home to over 100 fantastical cemetery coats-of-arms.

The Guardian of Tallinn.

A secluded art gallery hidden within the cellars beneath Tallinn’s medieval monastery.

"There's nothing there," and other lies the KGB told us.

This medieval Estonian tower provides access to a series of tunnels that have been home to soldiers, punks, and fine art.

Estonia's largest creative city is a vibrant bohemian hub located within a former industrial complex.

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

A former imperial sea-fortress and Soviet prison.

Disused seaplane hangar gets a second life as the jaw-dropping home of Estonia's museum of maritime history.

Villas that once served as playgrounds for the rich now fall away in decay.