We are taught that the ram's horn, or shofar, we blow on Rosh Hashanah has tremendous mystical powers. In the Beis Hamikdash they took advantage of a simpler and more practical aspect of a shofar: it makes a great anti-theft device.
After building a simple Lego model of the Second Temple (more about that here) I decided to put together a set of all three Temples at the same scale. Although the First and Second Temples were quite similar, there were a number of differences between them, some of which can be seen in the models below.