The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

Baltimore's classic clock tower was once topped by a rotating, 20-ton medicine bottle.

The first declared National Monument in the United States.

Avoid gangster interaction while window-shopping.

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

This simple Manhattan salt house is artfully shaped... well, like a giant granule of salt.

Self-sufficient greenhouse floating on the Hudson River.

America's greatest forgotten garden and the former stomping grounds of Son of Sam.

A tree that grows parallel to the ground was declared Brooklyn's "crowning curio" by the poet who saved it.

The sea once considered an ecological wasteland is now called "crown jewel of avian biodiversity" by scientists.

The 28-foot granite map plots the locations of 40 theaters in New York City.

Amid the marketing blitz of modern Times Square is an elegant holdover from its showbiz glory days.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

An unassuming secret door once led to a legendary watering hole.

Peace Park and the Atomic Bomb Dome.

A plaque marks the site directly below the mid-air detonation of the atomic bomb over Hiroshima.

Once a black market electronics marketplace, now an otaku shopper's paradise.

This Buddhist temple is home to the graves of the Japanese national legends, the 47 Ronin.

This bridge was constructed from the rubble of the infamous Bastille.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

This intricately carved and hilariously huge bed was such a famous symbol both Shakespeare and Byron used it in their writing.

The television series' iconic giant foot was borrowed from this classical painting.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

A six-ton wedding present for the King of the Scots.