Infamous marsh filled with toxic waste, World War II-era London rubble, and dead mobsters galore.

Curious crustaceans support an obelisk from ancient Egypt that now stands in modern-day Central Park.

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

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

One of the last few places in Manhattan that employed a pneumatic systemic keeps it on display.

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

Lie in a hammock where George Washington stood.

An artist's cute bronze subway sculptures belie his violent artistic past.

Elevated freight railway turned wildly successful urban park.

The most confusing clock in New York.

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

Play heads or tails with thousands of different coins.

Two thousand artifacts from around the world collected by one woman who loved to travel.

An enormous, inside-out glass globe built in 1935.

What was once a true peninsula has now been filled in, causing the water to recede and leaving many streetside "waterfronts" and landlocked "islands."

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

Famously misunderstood wonder of the ancient world

The site of Paul Revere's historic two lantern warning.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

Hear the quietest sound from across the dome.

The first official clock in North America, it kept time for the Spanish government of Santo Domingo.

Built in 1512, the oldest cathedral in the Americas.