An acoustic anomaly with a mysterious cause sits in the heart of Tulsa.

A Route 66 filling station that was designed to resemble the Hagia Sophia, and is now the symbol of an arts district.

A half-size replica of the World Trade Center towers above Tulsa.

These massive mitts are made of 30 tons of devotional bronze.

The small first-floor apartment where the author wrote her Pulitzer Prize-winning book 'Gone with the Wind.'

Rare videos and memorabilia await visitors inside this unique store.

The record holder for the world’s largest peach.

The famous boat that once ferried Bogart and Hepburn still floats in Key Largo after being abandoned for years.

A 400-foot-tall tall map of Chicago makes this once-ignored building stand out.

A spectacular remnant of an Adler and Sullivan masterpiece that was destroyed in 1972.

This collection of ferns from across the globe is the largest assortment in the United States.

Tombstone of a dog that greeted passengers at the Southern Railway Depot.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

Look closely and you’ll notice that the color changes a third of the way up the tower.

Unique tower has outlasted a takeover of the company.

This neoclassic cathedral also houses what is believed to be the oldest clock in the Americas.

The tomb of the mythological founder of Padua is not hidden in some obscure crypt, but stands right in the middle of the city square.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

Known for centuries as the famous Roman emperor's burial place, this monument is actually something else.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.