ATHENS—Georges Kalaras used to view with pride the sports hall built near his home here for the 2004 Olympic competition in rhythmic gymnastics and ping pong. Now, he gets mad every time he jogs by.

"Look, it's locked!" shouted the 38-year-old Mr. Kalaras, who works for the Athens city water company. Two stray dogs tangling with each other behind a padlocked metal fence accounted for the only activity in the complex, which seats 5,200 people.

Mr....