This Pacific Heights home is a fascinating building. It was probably built in the 1990s. The exterior siding is a shiny plastic or lacquered metal, the garage doors stainless steel, and the blocks of rock are a rough texture contrasting with the smooth, slick surfaces that predominate. The two windows and garage doors are divided by a seam for some reason. The industrial HVAC box with aluminum fins on the roof is not what you would expect to see exposed in such a tony neighborhood where the homes are large turn of the century mansions. The trellis on the far left side wall of the courtyard is made of glass. Yet, the most fascinating element of the building's exterior is the small rectangular opening in the lower part of the stone wall.