"as sombrero pillbox iii" is located on matapang beach west of matapang park, about in from the high tide line. it is a two-room pillbox with a "complex configuration" of six walls; its west-facing wall is thick and has a gun port commanding the center of tumon bay. entrance and an air vent come through the east wall. it was built of steel-reinforced concrete including beach rubble, and, as of the nrhp listing date, was in "excellent" condition. there are "impressions of tabi prints and a possible japanese character" in the cement roof, which is about thick.