Doomed fiberglass mammoth in one of the tar pits.

La Brea Tar Pits

Los Angeles, California

Just east of Beverly Hills lies the "Death Trap of the Ages." It's the La Brea Tar Pits, which have spread the scent of petroleum over this part of L.A. ever since the city was founded -- and for tens of thousands of years before that. The tar pits are famous for the countless prehistoric animals trapped in them: mammoths, mastodons, bison, camels, giant sloths, lions, horses, bears, dire wolves, saber-tooth tigers. No dinosaurs -- they'd all died out by then -- and thus far only one human has been found, who fell in roughly 12,000 years ago.

The tar pits are the only active urban Ice Age excavation site in the world. Scientists began digging bones out of the pits in 1901 -- over 3.5 million so far -- and they still haven't reached the bottom. In 1954 a public viewing platform was opened over the big "Lake Pit." Half-sunk fiberglass animals were added in 1967, along with recorded bellowing broadcast over speakers, to provide some melancholy context.

Ten years later the Tar Pits Museum opened, enlightening visitors about the fossil gumbo just outside the door. One wall of the museum is filled with nothing but wolf skulls. There's a glass-walled fossil lab where tourists can watch scientists clean recently excavated bones, and a pair of fake mammoth heads that can be manipulated in a tusk-on-tusk battle. Don't step in that sticky tar, mammoth, or you're done for.

The pits are still bubbling away, and visitors walking from the parking lot have to steer clear of the traffic cones on the lawn; they mark the spots where tar is still seeping out of the ground.