Magnificent New Deal Murals evoke a time when New York City harbor was one of the world's greatest and busiest ports.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

Possible relics of the ancient Roman city are hidden in this restaurant's façade.

Macabre astrological automaton clock dating to the late 1400s.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

More than 5,000 artifacts donated by the people of the city, plus a room entirely devoted to the band U2.

Hear the quietest sound from across the dome.

A curious fountain that has no water and includes Satan, a crab, and 9 giraffes.

The comedy and tragedy of Oscar Wilde is preserved in a Dublin park, captured in a sculpture of colorful stone.

One of Ireland's most infamous prisons for rebels including men, women and children.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

This permanent collection of preserved bodies taken from Irish bogs is one of the leading authorities on such morbid mummies.

The modern birthplace of Irish freedom.

Currently housing a corporate bank branch this building at the southern tip of Manhattan was once the gateway to luxury vacationing.

This anonymous businessman sculpted in bronze became an enduring memorial after 9/11, and had been mistaken by rescue workers for a survivor in the rubble.

This curved Manhattan building was built to house the opulence of John D. Rockefeller's oil empire.

A bit of retro transportation flair preserved in the world's largest department store.

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.

Surprisingly aquamarine waters fill deep lakes formed at the end of the last ice age.

Limestone caves with spectacular showcase chambers.

The small peaceful island off the Venice tourist circuit is where the city began more than 1,500 years ago.

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

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.