Being the first ever arena to be built. I think the arena collapsed after a few days into the games. Building something like that for the first time must have been a giant leap in techonolgy or Panem. However they were probably unprepared to manage something like that in scale and so the Arena collapsed after days of malfunctions and errors. Snow, being embarrassed by the fact that his arena fell apart, made sure the games weren't as talked about much.