Sections of the iconic limestone columns have been left uncleaned as a reminder of the city's polluted past.

Look closely and you’ll notice that the color changes a third of the way up the tower.

The Pennsylvania landscape depicted by a quarter mile of mosaics made from used road signs.

Soaring over the Niagara Whirlpool since 1916.

The only castle in North America to ever house European sovereigns.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

The land is home to swimming ponies and a legendary 18th-century treasure.

Largest Roman Catholic church in North America.

A geological mystery on Camelback Mountain.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

Every equinox this Maya pyramid puts on a spooky ancient light show.

This Niagara Falls tourist trap is a world bright with neon and curiosities that will inspire love, hate, or a mixture of both.

Equal parts record-breaking temple to consumerism and bizarre fun park, it's more than you think it is...

A 200-year-old bar in the historic French Quarter refuses to give up its place in history, nor its role in securing ours.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

The celebrated eyesore created by starry-eyed sweethearts.

This magnificent museum claims to house the cranium of a disciple and the skull of a pope.

Go surfing on this urban wave, "hacked" by local surfers.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.