The unexpectedly beloved remnants of a controversial thermal power plant.

This mansion oasis contains gardens, sculptures, and fountains just off the busy Plaça Kennedy in Sant Gervasi.

An open-air "garden" of mural art that changes weekly.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

Legend says this sacred tree was a gift from goddess Athena.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

Hidden beneath the streets of London is a secret subway that only carried mail.

The famous 102-year-old circus elephant was struck and killed by lightning.

These giant metal horses graze on a hilltop near the Montana highway.

An entire town preserved as a historic landmark.

This beautiful ancient site is dotted with perforated sandstone pillars considered sacred by some Native American groups.

Resting place of Hollywood's immortals is also site of summer film screenings.

One of the world's oldest universities houses an incredible collection of anatomical models, mummified body parts, and human bones.

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

This geometric feat is a testament to the Incas' mesmerizing architectural abilities.

Underneath the bustling city streets, a hydroponic farm grows unique herbs in an urban oasis.

Sandstone rock formations that look like they belong on the cover of a progressive rock album.

These abandoned huts still hold the remains of an early 20th century Australian researcher's work.

These giant volcano sponges in Antarctica are thought to be the world's oldest living animal, at 15,000 years old.

Largest sub-glacial lake ever discovered.

One of only two civilian settlements in the desolate lands of chilly Antarctica.

Russian Orthodox church built on an Antarctic island.

The world's largest neutrino telescope searches for secrets of the universe at the South Pole.