This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

The corpse bride of Portugal.

Local lore says the devil built this beautiful medieval bridge to help a fleeing bandit.

This small chapel is built of human bones and decorated with a golden skeleton.

This fairy-tale, neo-Gothic church in the Azores is a world of magical realism.

Houses are tucked between, on, and underneath giant boulders.

The medieval castle built as headquarters for the Pope's secretive Knights Templar.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

An eccentric inventor's castle home with its own indoor weather system.

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

The eccentric mansion of one the most popular horror authors of modern times.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

The oldest Italian café in Boston, this spot also serves as a veritable museum of vintage coffee ephemera.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

Thousands of well-dressed mummies below a monastery.

Art and a pun, all in one.

Pompeii's less famous neighbor is still revealing her secrets.

A fantastic castle rumored to be the birthplace of King Arthur.

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

The site of London's first coffee house has been serving refreshments of one kind or another for 360 years.

A whimsical village of unique treehouses resides in a Washington forest.

Spend the night in this formerly abandoned traditional Scottish village.

Ruins of the elaborate house where the enigmatic costume designer threw glamorous parties for New York's theatrical elite.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.