The Punta Mulas lighthouse entered service on June 1, 1896. It was designed by Francisco de Albacete and built by the government itself on a promontory near the port of Isabel II, to illuminate the Vieques passage and to guide navigation into the port, which exported cattle and various crops. The building measures 53 feet long by 35 feet wide. It closely resembles the Arroyo lighthouse, with which it shares the pattern of circles and rectangles in the cornice, and is almost identical to the one at Puerto Ferro, just opposite on the south coast of Vieques.

The building was initially painted light gray with white details and baseboard. The 28-foot tall octagonal tower is at the center of the structure, its sixth-order lens projected a red light eight miles away; currently the light is produced by a beacon fed by solar panels. The two Vieques lights are the only Puerto Rican lighthouses built originally with two doors, of which the rear is flanked by two circular openings (bull’s eyes) which ventilated the bathroom and the kitchen.