This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

A man's head is enshrined beneath a statue near the first building constructed for the modern Olympic Games.

This black sand beach was crafted from volcanic explosions including the historic Minoan eruption.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

A stunning church overlooking the water that you will have all to yourself.

Luminaries of all stripes have sipped strong Greek coffee at this cafe since 1839.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

Ancient serpentine sacrifice holder that has stood the test of time.

A sharp sculpture made of thousands of pieces of jagged glass.

The first national memorial to honor all women suffragists stands on land where suffragists were once imprisoned.

The Old Courthouse takes visitors on a captivating trip through St. Louis' timeline.

This modern castle sat empty for decades before a fire inspired its builders to complete its luxury halls.

These unusual rooms on wheels are holdovers from the 1960s.

This train station inspired the name of a 1970's rock band and provided the backdrop for their album cover.

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

Railroad officials in the early 1900s sought to spare travelers the sight of Roman soldiers’ private parts.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

A home that witnessed Civil War combat on the Sunken Road has the battle scars to prove it.

This sandwich shop has a century-old elevator behind a sheet of plexiglass.