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

One-time largest man-made structure in the world will be a park in 30 years.

The longest continuous underwater road in North America was built at the insistence of Franklin Roosevelt.

A preposterously luxurious hotel with gold-plated iPads, Rolls Royce chauffeurs, and a staff that trains by watching "Downton Abbey."

On any given day this sprawling market houses literally tons of government-regulated gold, gems, and precious metals.

This monument to a veteran of the Mexican-American War is one of only two in Manhattan that serve as an actual mausoleum.

There must be a pun in this haystack somewhere...

The site of the deadly Triangle Shirtwaist Factory Fire.

Avoid gangster interaction while window-shopping.

Spinning silently in the lobby of an Art Deco masterwork is a massive vintage model of the Earth.

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

Lie in a hammock where George Washington stood.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

Copenhagen's celebrated theme park and gardens.

Time capsule of a museum, in which the Soviet Union remains alive and kicking.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

Once the world's largest reinforced concrete structure, this abandoned bridge now beckons urban explorers.

A backdoor to Machu Picchu that only the most foolhardy infiltrator would attempt to breach.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

A granite monument honors a beloved World War II canine mascot.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

Corn-inthian columns with a uniquely American take on neoclassical architecture.