An overlooked memorial honoring the local Washington residents who died in World War I.

There’s a hidden military meme engraved on the World War II Memorial.

The U.S. Fish Commission’s effort to mass produce carp.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

Art deco landmark on the outskirts of Washington, D.C.

Once the supplier for noteworthy projects like the National Cathedral, this old brickworks now lies abandoned.

A tribute to the pop culture icon overlooks this Washington D.C. intersection.

A celebrity from the late Cretaceous period.

Through the decades, Black music stars have performed at this historic hub for music and the arts.

Washington D.C.'s most famous pianist, composer, and bandleader still tickles the ivories outside Howard Theater.

A pair of black granite tails dive into a sea of grass in landlocked Vermont.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

A very classy 1920s-era bar right in Grand Central Station.

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

A Hell's Kitchen synagogue that has counted stars of stage and screen among its congregation.

This nearly invisible wire transforms much of the city into one big, symbolic home on the holy day.

A large boulder marks the place where the island of Manhattan was purportedly "sold" to the Dutch.

A beautiful, creepy 19th-century castle stands incongruous in rural Vermont.

A 60-foot-tall tower provides unparalleled views of the southern Green Mountains.

The largest battery in New England sits atop a Massachusetts mountain.