In the 19th century, this was the center of Boston's Black community.

A tiny plaque marks the location of the water source that facilitated the birth of modern-day Boston.

This area was once known for being a lawless haven for rough-and-tumble sailors, earning the maritime-themed nickname "the black sea."

A former waterfront market is now in the center of town due to some interesting Boston engineering.

These whimsical works of art tell the story of the city's past and present.

Tucked in a nondescript downtown Brooklyn mall is a bar containing a remarkable turn of the century anatomical wax collection last seen in 1920s Berlin.

This one-block alleyway is stuffed with street art that is colorful, cultural, and intensely political.

Guns that have been defending San Francisco since 1904.

Since 1973, this block has been home to the most concentrated collection of murals in San Francisco.

This partially buried wreck is one of the most complete of its kind but is only revealed when the sea allows.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

Golden Gate Park's historic collection of plants.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

A winding path built in secret on the edge of the continent.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

This shop specializes in oddities and Victorian-inspired wonders.

A huge musical instrument played by the ocean.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Tiny memorials honor individual victims of the Holocaust.

When German-Iraqi relations broke down, this embassy was vacated post haste.

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.