Archaeological sites and great food inside the island's largest mangrove forest.

Legend tells how a Spanish soldier disappeared from this isolated sentry box without a trace.

This chapel on a cliff is renowned for its healing powers and was founded on the site of a supposed divine intervention.

Everyone from Alan Ginsberg to The Rolling Stones has stopped by this classic dive bar.

This bleach-white graveyard overlooking the ocean is accessed through a tunnel.

This colorful gate stands as an entrance to the walled city of Old San Juan.

This tiny home was originally a narrow alleyway.

Once damaged by Hurricane Agnes, this bridge is now on the National Register of Historic Places.

One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

This local mascot has been a presence in the area since the 1960s.

This bridge over D.C.'s Rock Creek Park is sometimes called the "Buffalo Bridge" because of its four buffalo sculptures, which were cast from a single piece of bronze.

A farmhouse where soldiers left their marks on the walls and attic

The phrase "the shot heard around the world" was coined after a skirmish at this bridge.

The unique location where the former president was rapidly sworn in.

A historic Maryland home that once belonged to a man who has been called "the most insignificant" U.S. Supreme Court justice.

An aptly-named street near the birthplace of the modern LGBT rights movement.

An oft-overlooked, magically musical monolith that stands majestically between Arlington Cemetery and the Iwo Jima Memorial.

Fake subway tiles were installed to cover a design that resembled the Confederate flag—it's unclear if the resemblance was intentional.

An unassuming secret door once led to a legendary watering hole.

A mosaic made of materials gathered from this Brooklyn community adorns the walls of this tunnel.

The ballpark in "Pigtown" where the Brooklyn Dodgers made their name was replaced with a huge apartment complex.

19th century cemetery hidden in Brooklyn's Prospect Park.

This elaborate tunnel is the first structure composed of cast concrete in the United States.

A tree that grows parallel to the ground was declared Brooklyn's "crowning curio" by the poet who saved it.