Compluvium/Impluvium: This design was created to catch rainwater from the roofs when it rained. The water would flow from the compluvium into the pool like impluvium. I thought this was a pretty clever invention they had, almost like modern day rain catchers for gardens.
Pompeii, House of Venus in a Shell. On the rear wall of the peristyle are three large paintings on a blue background. The left hand painting is of the god Mars shown standing naked on a plinth while holding a lance & a shield. Around him the foliaged garden is teeming with bird life. AD 79 eruption