I Street Bridge is the heaviest swinging center bridge in the United States.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

This cemetery served as the only official burial grounds in Cambridge for nearly 200 years.

Allowing humans and fish alike to migrate from freshwater to saltwater and back again.

The largest clown school in Britain offering accredited degrees.

The world's longest outdoor covered escalator system transports commuters through Hong Kong's hilly terrain.

Eighty million natural history specimens call this gargantuan museum home.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

One of the largest underground systems runs under Canada's largest urban center.

A historic Montreal market that was the city's agricultural hub for over century.

The rotting skeleton of a shoreside fun fair that was destroyed by fire and storms still haunts the Brighton ocean view.

The oldest working mechanical clock in the world.

The yawning maw of this pagan visage is said to bite off the hands of liars.

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

Erotic art covers the walls of the largest ancient pleasure palace.

The Emperor Tiberius' palace of debauchery.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

Op-art architecture designed for happiness.

Baroque celebration of the end of the Great Plague of Vienna.

The Habsburgs' royal collections of art and wonders.

This Swedish astronomical clock was in storage for almost a century before its glorious workings were put on display once more.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

An out-of-place slice of France, smack in the middle of Shanghai.