PUYALLUP — One of the oldest buildings on the grounds of the Washington State Fair was destroyed by fire early Monday, just hours after the spring fair concluded Sunday night, spokeswoman Karen LaFlamme said.No one was inside Evergreen Hall when it caught fire and no one was injured.One piglet from the petting farm died; 49 other animals — including a miniature donkey, goats, alpacas, turkeys, ducks, chickens and rabbits — were safely moved to a nearby barn by firefighters and fair staff. A veterinarian treated some that had breathed in smoke, LaFlamme said.The fire broke out around midnight and went to two alarms before it was extinguished by the Central Pierce fire department. The cause of the fire is under investigation but it apparently began in a food concession area in a corner of the building. The Sales Lunch restaurant has been operated for generations by the same family and is known for its onion burgers and Krusty Pup corndogs.Evergreen Hall was remodeled last year to house the agriculture and floral departments at last fall’s Washington State Fair. During the spring fair, it housed the petting farm and Future Farmer of America displays.There’s no dollar estimate yet of the loss, but the building will probably be replaced, LaFlamme said. Floral and farm displays may be exhibited in a tent in the meantime.The traditional state fair held in September is one of the largest in the nation.