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

从露封闭的建筑的转变，就可能是追求门收入的开始。

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

那就是罗马的椭圆型露了，基本上是综合功能的体育。