An artsy hidden staircase leads to breathtaking views of San Francisco.

This tall and trim architectural oddity is one of the skinniest buildings in San Francisco.

A shining, cold, black organ lies in San Francisco's financial district.

An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

Since 1973, this block has been home to the most concentrated collection of murals in San Francisco.

This concrete tangle of square pipes has stood as a proud thorn in the city's side since the '70s.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

This one-of-a-kind Roman arch is not actually dedicated to the god Janus.

A graceful natural rock formation stands astride the point where the Gulf of California meets the Pacific Ocean.

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

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

This massive and unusual rock formation near Okotoks is the world's largest known glacial erratic.

For this chef, an active volcano is his oven.

Pilgrimage site for star-crossed lovers.

This centuries-old pub boasts a collection of more than 4,500 snippets of neckties from around the world.

This natural wonder is disappearing at an alarming rate.

This ghost-town bar has bullet holes and plenty of stories lurking within its walls.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

The sophisticated hydraulic system of the Nazca civilization.

After surviving abandonment, this powerful Latin American mural is alive again.

This oak sculpture at the edge of a small woodland is nine feet tall and shrouded in mystery.

L. Frank Baum wrote part of the "Wizard of Oz" series in this wooden Victorian beach resort.

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