The Financial District, predominately a commercial center of historic banks built on Gold Rush fortunes and high-rise office buildings, offers workers a smattering of upscale apartments and condominiums and the demand is growing. Four-star, expense account restaurants and hotels, as well as services of all kinds, are never more than a block away. Green space can be found if you're persistent: Jackson Square Park, near the Embarcadero Center, is the perfect place for a refreshing, sunny picnic lunch. Hidden between the famous TransAmerica Pyramid and another high rise, you'll find TransAmerica Redwood Park, a tiny sanctuary where busy stockbrokers take a break to watch Chinese grandmas practice their Tai Chi.