The change from the unroofed stadiums to sealed off buildings maybe the beginning that tickets were sought.

从露天场馆到封闭的建筑的转变，是追求门收入的开。

That must be the oval unroofed amphitheater in Rome. It was basically a stadium with comprehensive functions.

是罗马的椭圆型露天竞技场了，基本上是综合功的体育场。