This SU served as a drain within room 22 associated with the later floors. It creates a small rectangular cavity which leads into the large drainage channel below through a rough semi-circular cut in the underlying slab. The extension of the feature under the finished floor surface indicates that the drain was an earlier construction. Evidence from the fill, including a concentration of coins and small special finds which may have accumulated over time, supports this interpretation. Nails and metal fragments found may indicate that the gutter was once covered by a grate.