The birthplace of San Diego--indeed, of California--Old Town takes you back to the Mexican California, which existed here until the mid-1800s. Bazaar del Mundo is a 1930s-era motel that was turned into a collection of shops selling well-chosen south-of-the-border wares. The complex suffers a tourist invasion daily, but who can blame them? The Bazaar is vivid, intimate, and anything but plastic. It's also a popular for California-style Mexican meals and margaritas.

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, following the San Diego River upstream to the Mission Basilica San Diego, and just a few miles beyond, 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.