This crumbling medieval basilica once attracted pilgrims by the thousands to collect a miraculous dust that formed above the saint's tomb.

The ancient latrines of the Greeks, in all their public glory.

Seven early Christians were sealed into a cave where legend has it they slept unharmed for centuries.

Carvings in Turkey's Marble Road may have directed ancient Romans to a hidden brothel.

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

A charming beach town in Turkey captures all the colors of the rainbow.

A deadly ancient portal to the underworld.

Roman ruins top white travertine terraces formed by ancient hot springs.

This arch granting triumphal entrance into Antalya was designed to honor the emperor's visit.

The best-preserved ancient theater in the world.

The largest Neolithic ruins in the world hide a notably clean prehistoric metropolis.

A sacred lake with thousands of sacred carp and a biblical history.

This hunter-gatherer architecture is believed to be the oldest religious complex known.

Mausoleum and Holy Seat of Antiochus I of Commagene.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

The "lovely red Vega" of the legendary record-settling pilot.

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

Washington's iconic carousel has a nice piece of Civil Rights history.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

The most decorated dog of World War I is preserved in the Smithsonian.

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

Home to items never before seen by the public.

The oldest continuously operating fish market in the United States.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.