This building is to the west of the square in front of the Four Small Temples (II,VIII,2). It was excavated in the years 1885-1886 by Rodolfo Lanciani.

Surprisingly (in view of the proximity of the temples) this seems to have been an industrial building, like buildings II,VIII,7 and 9. A small basin is found in a little room in the north-west part. There was a long basin against the west wall (10.87 x 1.20). The building is probably Hadrianic. It has been suggested that it was a fulling mill, but there is no good evidence to support this interpretation.