La Cárcel's main entrance faces the street, passing through a 6 cm. thick concrete and sand wall buttressed by regularly-spaced upright wooden (matazarnos) beams supporting the upper floor joists. The interior wall surfaces show that the exterior concrete face was backed by horizontal lathes of bamboo and reinforced with barbed wire. The upper story was accessed by a staircase resting atop a squared base across from a secondary door opening on the structure’s east side. A number of vertical openings served as windows for the second story, whose floor, having been described as constructed of cement and lime, may have survived until recently.