Concrete igloos standing across from what remains of the Michigan Central train depot.

A Beaux-Arts triumph rises from decades of decay to become the heart of a new innovation district.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

This railway-turned-greenway provides a pedestrian link in downtown Detroit and celebrates urban artwork.

The bones of an old zoo crumbling in the shadow of a new one.

The Beaux-Arts aquarium boasts a vast collection of saltwater and freshwater fish on an island in the Detroit River.

Glass and concrete building designed by Albert Kahn.

One man's attempt to create an artistic wonder on a run-down block in Detroit.

The concrete shell of an industry giant remains as a playground for graffiti artists, auto scrappers, and paintball warriors.

Standing guard on top of an old, vacant ice cream shop.

What's left of the ruins of the 1893 Columbian Exhibition, or World's Fair, also known as the White City.

First planned industrial community in the United States.

The restored and active Victorian-era final resting place of San Francisco.

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

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

San Francisco's newly reopened hands-on science museum.

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

A modest reminder of treacherous waters at the Golden Gate.

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

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