Upper King Street (north of Calhoun Street) is a Charleston area frequented by locals and savvy visitors. It's a mini-city in itself, ideal for strolling, and one of the few parts of the city with both street-side dining and a flourishing nightlife. The liveliest and most interesting sections are between Vanderhorst and Spring streets (about five blocks). This area is also referred to as Charleston's "design district".
The mostly 19th century buildings are a hodgepodge of bars, restaurants, book and record stores, music and performing arts venues, both upscale and downscale clothing stores, and miscellaneous odd shops that defy description. This commercial area has had quite a few development spurts in the past few years, so you'll see buildings with fresh facelifts side by side with their lesser-developed neighbors. The resulting mixed bag of old and new adds to the charm and atmosphere. The crowds are as eclectic and lively as the businesses, so it's a great place for people-watching too.
Recommended restaurants are: Basil (Thai), Rue de Jean (French) and AC's Bar and Grill (pub food). See the Charleston City Paper (available free at many businesses) for operating times and addresses. Charleston maps are also available at the Visitor Center, 375 Meeting Street.