Between each pair of milecastles lay two towers.

两座城堡之间有两座塔。

Between each pair of milecastles lay two towers.The stone wall was to be 15 Roman feet high and 10 Roman feet wide.

在每对 milecastles 之间有两座塔楼。 石墙高 15 罗马英尺， 宽 10 罗马英尺。