During the holidays, a vintage subway train whisks New Yorkers back in time.

One lonely, modern pyramid has gone from corporate think tank to deserted boondoggle.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

The second largest waterfall by volume in the U.S., Willamette Falls is outdone only by Niagara in the amount of water that is pushed northward.

No one knows how this Pacific Northwest spruce tree came to have so many trunks.

Where Nor'easters go to die.

Tasked with beautifying a disused stretch of industrial land one artist filled a hole with grass.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

This abandoned bridge to nowhere stands secluded in the woods of a Cleveland suburb.

The crumbling structure is a rare surviving relic of the area's bygone mining industry.

One man's ambition created this psychedelic log home.

It took more than 300 years to build this church, which is home to two sacred vessels believed to hold the blood of Christ.

The oldest church in Mantua was buried for centuries under the facades of other structures.

A room filled with frescos that make it seem like the walls are crumbling down while giants die in despair.

The Roman city was the birthplace of various emperors and is home to one of the empire's most impressive architectural feats.

Long tunnels run under the ancient chariot racing circuit to the tower.

Stunning Roman aqueduct used for 1900 years and still standing.

The best-preserved ancient theater in the world.

The remains of an ancient Roman city are hidden underneath Bologna's beautiful public library.

This exceptionally well-preserved ancient marvel also houses a small museum dedicated to Jordanian folk tradition.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

This Roman arena once played host to bloody gladiatorial battles.

This architectural oddity is an oasis of green on the outskirts of Valencia.