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

The world's oldest Jewish library was founded by Sephardic Jews in 17th century Amsterdam.

A retro walk through the history of the tube.

A rare example of a German cemetery with traditional grave markers dating back several generations.

These passages carved from the Antarctic ice hold strange shrines to the harsh southernmost climes.

Japanese national treasure originally built in 593 CE.

A plaque marks the site directly below the mid-air detonation of the atomic bomb over Hiroshima.

This 14th century castle withstood years of battle but is now sliding off the hills into the Danube.

The longest stone bridge in England has an impressive history that dates back over 700 years.

Twisted girders are all that remain of an Icelandic bridge that was wiped out by a combination of volcanic heat and glacial floods.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

This natural wonderland is a unique chance to explore a Carolina bay, a mysterious geological formation of unknown origin.

Rebuilt remains of a temple to Roman god Mithras.

The most elaborate of 12 medieval arched doorways to the old city of Burgos.

This 15th-century cave complex is one of the very few monasteries to stay open throughout World War II and the Soviet regime.

The carved medieval stones stand near the ruined abbey's parking lot.

Legend has it the famous Robin Hood would attend mass at this 12th-century Cistercian abbey in Sherwood Forrest.

In the ruins of Glastonbury Abbey lies the alleged resting place of the legendary king.

A remarkable medieval structure born from a 14th-century disaster.

These imposing walls and towers look more like the ruins of a fortress than a monastery.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

One of two Irish-style round towers in Scotland, this structure has mysterious origins.