The fact that variants of palla are all street games, and that they are clearly related to real tennis suggests something of the development of the latter sport's court. It had been assumed that a real tennis court developed from the layout of monastery cloisters. This is mainly due to the early popularity of the game among clerics, and similarities of some court features to a cloister. However, this theory has two problems. Cloisters are usually square, while a tennis court is much longer than it is wide. Secondly, some of the similar features of tennis courts were actually introduced in the 16th century, and earlier layouts were less similar to cloisters. The study of palla has led many to suggest that the first tennis courts were made by those who wanted to play the street game, but could afford a more private and much cleaner setting. Similarities to cloisters in later court designs could either be coincidence, or intentional innovations. The proportions of the court and features such as penthouses and windows could easily relate to medieval streets.