It's hard to imagine a trip to San Francisco without a Chinatown visit. Whether you make the grand entrance into Chinatown beneath the dramatic portal at Grant Avenue and Bush Street, or perhaps just happen upon the district while making your way about San Francisco, you can't help but be impressed by this city-within-a-city. Along its streets, exotic ingredients are hawked, silks and jade are proffered, and colorful mementos are sold to tourists. If you happen to be planning a visit in February, do your best to catch the Chinese New Year celebration in Chinatown, one of the largest of its kind in the world outside of China itself.