A six-story treehouse offers spectacular views of New York's Finger Lakes region.

Pluto is still considered a planet in Ithaca, New York.

One of the deadliest American air disasters is nearly forgotten in Brooklyn.

This secluded ruin was once a home for exotic plants.

Sniff the Titan Arum's rotting flesh.

This striking arch, one of the first architectural elements constructed in Prospect Park, was recently restored to its original glory.

Try not to get slimed in Tribeca.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

The last living thing to come out of the rubble after 9/11 is now a symbol of hope and resilience.

A well-worn marker in a forgotten alleyway is all that remains of what had been one of Manhattan's most beautiful buildings.

Built hundreds of years ago this downtown iron barrier once protected a much despised king.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

The home of the first American-born saint is one of the only curved buildings in New York.

This city park was once a lookout point for George Washington’s army during the Battle of Brooklyn in 1776.

The New Central Library is a masterpiece of contemporary architecture in the midst of downtown Calgary.

Inside this Krakow church, an explosion of psychedelic color.

The final resting place of the author who gave us the Little Mermaid, the Ugly Duckling, and many more beloved fairy tales.

For over a century, it has been a tradition to raise a flag at the top of this 450-foot sandstone pillar on the 4th of July.

Take a dip in the world's largest mineral hot springs pool.

These markers are used to document elevation changes around the famed dam.

A natural swimming hole that was once a ceremonial center for Mayan priests.

Sparkling, calcite-covered skeletons of children who may have been sacrificed to appease an angry god.

Giant heads occasionally litter the industrial Houston neighborhood where sculptor David Adickes has his studio.