View looking down on to the House of the Vestal Virgins. The "house" occupies the whole lower half of the image.
The green grass with the three pools is the large courtyard of the "house"—porticos surrounded it. The 12 white columns on the far side of the green grass supported statues of the vestals.
The two or three storey structure on the right (east) side of the grass seems to have been the actual "house."