The only structure left with direct ties to the Salem witchcraft trials of 1692.

Venice's island of the dead.

A walk through the historic city center, under the streets of Seattle.

Once the most densely populated place in the world, this island is now a ghost town.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

A Civil War Museum with some notable medical antiques.

A health museum containing a 27’’½-foot intestine.

A small but immensely extravagant palace built by the "Night King."

An astounding collection of medical specimens, including bits of President Lincoln.

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

A small museum filled with over 1,000 clocks, and one particular clock calibrated to run until the year 9999.

The king of U.S. high points towers over every other peak on the continent.

A small section of Boise, Idaho maintains the unique culture and traditions of the Basque people.

Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

Once described as the "Eagle's Nest," this ruined ancient city rests on a remote mountaintop.

This historic stone bridge has an entire neighborhood clinging to its sides.

The sound of swaying stalks in this stunning grove has been named a governmentally recognized sound.

The centuries-old trees lining both sides of this dirt road may become Madagascar's first natural monument.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

Live a night as a Byzantine King, with a minibar and private jacuzzi.

This ancient subterranean megalopolis is known for the hot oil traps that were installed above each of its entrances.