Plaza Hall was originally erected in 1815 as a one-story adobe building to house the unmarried Indian girls of the mission. In 1868  Angelo Zanetta purchased it and proceeded to remodel the building which was in a ruinous state.  He tore down the  building and reused the good adobe brick for the outer walls of the present two story Plaza Hall. The new second story was of frame construction, with a fake front and a two-story veranda of the facade facing the plaza itself. The hope was that the Plaza Hall would be the County Courthouse.  However, when Hollister became San Benito County’s Seat, Zanetta remodeled the building to be his family home.

Many local festivities were hosted in the upstairs ballroom which had been rated as the finest dancing floor in this area of California. The floor had been constructed in such a way as to provide a “spring board” effect. The upstairs was used for meetings, rallies, and shows. For a time the town volunteer fire department held meetings there.

According to elderly members of the second generation of the Angelo Zanetta family, the original building was of adobe two stories in height, with a tile roof. Because the flooring was never laid for a proper second story, it was then never used for living quarters but had served for the storage of hay. The adobe walls of the first floor still remain but the house was rebuilt in 1888 as it now stands, with an upper story of framework and shingle roof. The small northern wing of frame construction was added at that time.

Angelo Zanneta’s daughter Victoria Zanetta sold the Plaza Hotel to the State Park in 1933.