This historic Pittsburgh tennis complex is a rare example of natural red clay courts.

This 16-foot, intricately detailed model of the Gearing-class destroyer has been called the most detailed model ship ever built.

One tiny triangular park commemorates the victims of a yellow fever epidemic—many of whom are buried right below the grass.

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

The 28-foot granite map plots the locations of 40 theaters in New York City.

One of the largest collections of Catalan literature and cultural materials outside of Spain, created by a community of 1960s expats.

A double agent hid information for the Soviet Union beneath this bridge for more than 20 years.

A blank headstone topped with a pile of pennies marks the final resting place of the infamous assassin.

This star-studded Old Hollywood restaurant is where fettuccine Alfredo made its United States debut.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

The final resting place of many of New Jersey's most famous residents, including U.S. history's most in-vogue antagonist, Aaron Burr.

A 19th century library favored by Edgar Allan Poe and H.P. Lovecraft, known by locals as "the Ath."

The first American axe throwing club.

The iconic D.C. restaurant where the Cuban Missile Crisis was negotiated, now a Walgreens.

This Great Depression-era creation was once known as the strangest house in the world.

A sculpture of the famous photograph stands on San Diego's "Greatest Generation Walk."

This Virginia town has been famous for its fried chicken since the 19th century.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

An obscure federal monument honors the French diplomat who served as Ambassador to the U.S. during WWI.

A drab two-story office space in Delaware is a hidden tax haven for Hillary Clinton, Donald Trump, and over half the Fortune 500 companies.

Two mermen, eternally spitting into each other's mouths.

A clone-tree in Washington Square Park sprung from seeds that went to the Moon and back.

This stately 19th century library pushed architectural boundaries at a time when the public library movement was just taking off.