==Retractable roof stadiums== 
 Retractable roof stadiums should not be included in this list, because it is a list of indoor arenas. Indoor arenas are buildings with a fixed roof. There is a number of retractable roof stadiums in Europe - apart of the two currently listed - and if there will be more appearing in this article the indoor arenas will be in the bottom of the list This has a logic, since stadiums are usually larger by capacity. If there are no objections I will remove stadiums from the list.