The Hall of Records was a government building in San Francisco in 1893. This building was a repository of the city's records.
During his time in 1893 San Francisco, Data, claiming to be a geological engineer, visited the Hall of Records several times searching for information about mining in San Francisco. Samuel Clemens heard of Data's activities via Ches Whitley and questioned him on the matter. (TNG: "Time's Arrow, Part II")