The Second Peristyle is the larger peristyle, and was, for Ancient Pompeii, an enormous garden surrounded by a portico. This peristyle was 45 by 40 meters, and had 46 Doric stucco columns, which were each about 4.1 meters high. It was overlooked by shuttered windows. 

The Second Peristyle was added at the end of the 2nd century BC. In addition, there were several rooms at the back of the peristyle which were added at the same time: the rooms of the gardener and a secondary entrance onto the  Vicolo di Mercurio.

(view of the Second Peristyle from the First Peristyle)