Twenty-three centuries ago, or so it's said, a couple of bored Roman centurions started tossing around a few handy boulders, attempting, in an early and distant relative of horseshoes and penny-pitching, to come closest to a designated smaller stone some distance away. Fast-forward and -westward to Aquatic Park on a recent foggy weekend, where the ancient game of bocce ball is still practiced by the third-millennium descendants of those imperial sportsmen. Upon graded lanes paved with clay, soil, and pulverized oyster shells, heavy metal balls are rolled or tossed at a smaller brightly colored ball, amid many muttered Italian oaths and shouts of triumph. Behind the court sits a little shack grandly monickered the Aquatic Park Bocce Ball Clubhouse (one member, Benjamin Tosi, has represented the U.S. at two world championships). Comfortable benches are available for spectators and kibbitzers. And you can't beat the location: a sheltered spot just uphill from the Municipal Pier with Alcatraz, Angel Island, and drifting sailboats as backdrop.