If you can look past the nearby sewer pipes, this urban sinkhole grotto is a mini-paradise.

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

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

These azure waters were thought to lead to the Mayan Underworld.

This brightly made over hotel hides decades of suicide, serial killers, and mysterious deaths.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

Cold war icon and onetime "hole" in the iron curtain.

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

Pre-Nazi swastikas adorn the sculpted pachyderms flanking this brewhouse portal.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

Holding multiple historical boats and an entire 19th century village, this New England attraction is the largest maritime museum in the world.

Home of Philip Johnson, one of the 20th century's most influential architects.

This exemplar of modernist architecture is meant to captivate and inspire students of the Cooper Union.

The crown jewel of the Queens Museum is a nearly 10,000-square-foot architectural model of the city originally built for the 1964 World's Fair.

100 massive sculptures in the Hudson River Valley.

Sniff the Titan Arum's rotting flesh.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

The end of the 4 Line is also the end of the line for 300,000 souls in one of NYC's most illustrious cemeteries.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

Ride the subways of yesteryear.

Mysterious 500-year-old tapestries depict a unicorn hunt.