The birthplace of San Diego -- indeed, of California -- Old Town takes you back to the Mexican California of the mid-1800s.
Mission Valley, which starts just north of Presidio Park and heads straight east, is decidedly more modern; until I-8 was built in the 1950s, it was little more than cow pastures with a couple of dirt roads. Shopping malls, motels, a golf course, condos, car dealerships, and a massive sports stadium fill the expanse today. Further upstream along the San Diego River is the Mission Basilica San Diego, and just a few miles beyond lies an outstanding park with walking trails. Few visitors make it this far, but Mission Trails Regional Park reveals what San Diego looked like before the Spanish arrived.