The best seat in the house on Oct. 4 was up on the roof at the Carnegie Science Center, though standing outside along the river bank wasn't too shabby either. A steady stream of guests braved the crowds who converged on Downtown for Pittsburgh Celebrates 250, a daylong celebration that ended with the largest fireworks display in the region's history. That was the draw for the 500 members and sponsors lucky enough to be invited to the VIP party hosted by the Allegheny Conference on the ground floor of the Science Center. An assortment of classic 'burgh foods, including pierogies and kielbasa with sauerkraut, kept guests busy as they mingled with organizers, politicians, foundation and corporate heads before the 10 p.m. blastoff. The Zambelli fireworks were spectacular, especially as seen through the eyes of George Zambelli Jr. and his brother-in-law, Michael Richards, who orchestrated the show from the top of five buildings.