An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

When it opened during the final years of the embargo, all the drinks and cigars were free.

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

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

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

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

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

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

A historic neighborhood church is reborn as a psychedelic arts collective.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

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

Home to items never before seen by the public.

The last of Philadelphia's wood-paved streets is now a landmark of terrible engineering.

The abandoned coal loading dock is a canvas for unsanctioned art.

The world's third-largest crystal sphere has sat in the Penn Museum since 1927 with the exception of one outlandish theft.

Enjoy a slice while browsing the world's largest collection of pizza memorabilia.

Current docking place of the SS United States, the fastest transatlantic ocean liner.

Dr Barnes' $25 billion private collection of art and arboretum.

Mural made of 100,000 pieces of hand blown glass, and until recently, the largest glass mural in the US.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

World's first "penitentiary," meant to be humane, drove men insane.

A layered tribute to the work of mosaicist Isaiah Zagar.

Iceland's largest lagoon is home to stunning multi-colored icebergs.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.