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

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

This tree has witnessed nearly 1,000 years of history.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

The first North American landing spot for James Cook on his third voyage of discovery in the Pacific.

On the Oregon coast is a natural hole that seems to be draining the sea.

There's something big lurking beneath the surface of this tiny Oregon park.

The park preserves a single, rare species of carnivorous plant that spells doom for unsuspecting insects.

A sprawling cave network created by a lone lava tube.

An old World War II hangar holds 20 vintage aircraft and the rare opportunity to take a ride in a 1940s warbird.

The original span of a high bridge across the deep Crooked River Gorge has been preserved for pedestrian use.

The world's last remaining store of its kind.

A gift from Japan, 17th-century lantern stands among the cherry trees at D.C.'s Tidal Basin.

The last remaining location of a drive-up hot dog stand named after a local pool shark.

Home of the only civilian casualty at the Battle of Gettysburg.

Experience the pivotal Civil War battle at this interactive museum.

An outlandish shoe shaped house built by an eccentric millionaire.

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

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

A 200-year-old bar with a cheeky name claims to have served Edgar Allan Poe his final drink.

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

Once America's tallest structure, now a Baltimore landmark.

It’s not hard to see why the historic Peabody Conservatory of Music’s library has been described as a “cathedral of books.”

The design of this historic domed church was influenced by Thomas Jefferson and intended as a statement of religious freedom.