Corn-inthian columns with a uniquely American take on neoclassical architecture.

The walls of the iconic dome are hollow and have a secret stairway.

An ear-piercing buzzer calls lawmakers to a vote with a series of long and short rings to form coded messages.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

A much-maligned monument to teetotalism.

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

The 28,000-year-old specimen is remarkably intact.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

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

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

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

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

One of many reminders of Tesla's scientific contributions overlooks the falls which inspired him.

The last remnants of Fort Pitt also hold the distinction of being the oldest structure west of the Allegheny Mountains.

The highest point in Tennessee, Clingmans Dome bears witness to the ravages of one type of insect.

The world's longest known cave system.

All you ever needed or wanted to know about America's favorite whiskey, but not a drop to drink.

This replica of the Greek structure is in the heart of Nashville.

Elvis's own personal tropical hideaway.

By day this New Orleans square is for pedestrians, but by night it is a kingdom of kittens.

The only rotating bar in New Orleans has been slowly spinning since 1949.

The state's oldest continuously operating museum houses more than 5,000 Civil War artifacts.