The last stop on our trip is the La Brea Tar Pits in downtown Los Angeles, where residue from an underground lake of oil bubbles to the surface and is known as asphalt. Because asphalt is incredibly sticky and because it's been rising up from the Earth for thousands of years, it has trapped scores of animals -- especially those that lived in the region between 10,000 and 40,000 years ago.
Excavation of this site has produced 1 million bones belonging to more than 231 species of vertebrates with the most common being the dire wolf followed by the saber-toothed cat [source: La Brea Tar Pits]. Today, it is the world's only active urban ice age excavation site.
The onsite Page Museum offers visitors the chance to look through large windows at a lab where bones are being cleaned and repaired. Films, talks and events for children make the past truly come alive.