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

This tiny home was originally a narrow alleyway.

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

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

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

The oldest playground in America.

From bench to vandalism to art, this silly prank seat was funny enough to become permanent.

Radical Bookstore and Community Space.

The 1920s child prodigy author was last seen here at her Brookline home before vanishing at age 25.

This Dutch-styled residential building was originally a cocoa company's World's Fair showpiece.

This upscale streetwear store is hidden behind a fake Snapple machine in the back of a deli.

America's original house of worship for Spiritualism, the religious movement based on communing with the dead.

Painstakingly built dioramas sit unnoticed in a Boston office building.

The history of the tea trade is told in bas-relief on this historic pair of Boston doors.

This candy-colored storybook village originated as a 19th-century Methodist campground.

The oldest platform carousel built in the United States continues to delight children in Martha’s Vineyard.

The filming location of a shark attack in Steven Spielberg's famous shark movie.

A beacon atop a downtown building provides Bostonians with weather forecasts and baseball news.

Dedicated to nine marines from Massachusetts who perished during the Beirut bombings.

The unusual burial monument of Arizona's first governor.

A geological mystery on Camelback Mountain.

The fading, forgotten remains of a once bright and booming factory.

The last remaining 19th-century tenement from Boston's old West End neighborhood.

The key to turning shifting dunes into the green oasis of Golden Gate Park.