The oldest building on the site—la cocina—was originally a single room with a fireplace on its north wall. It was the only structure on the property when José Antonio Navarro purchased it. The Navarros added rooms to either side of the original room, so that the building became rectangular, running north to south parallel to Laredo Street. It is thought that the north room was used for storage; the original, central room used as the kitchen; and the south room used by the cook or other servants as living quarters. There are porches in both the front and the back of the building, to the east and west respectively. Basic square columns support the low shed roofs of each porch. The walls of the kitchen building are a combination of limestone block, rubble, and stucco. During the restoration in 1962 for the San Antonio Conservation Society, the kitchen building withstood the most change of all the historic buildings. As planned, the city of San Antonio widened Nueva Street. In doing so, the southern five feet of the original limestone walls were demolished. Brooks Martin supervised the construction of a replacement south wall of concrete block with a replica window. Then, the new wall was covered with stucco to blend with the other historic walls. If it were standing today, the original south wall of the kitchen building would extend beyond the stone mural wall and onto the sidewalk running along Nueva Street.