The Town Hall of San Sebastian is located in the historic Gran Casino de San Sebastian.

The casino was a major summer attraction, so the original purpose of the building was to house it. The architects Adolfo Morales de los Rós and Luis Aladrén Mendivil won the competition for the project. The building process lasted from 1882 to 1887, and the casino opened in July of that year. After the concession was returned to municipal control, on January 20, 1947, it was reopened as the updated town hall. Eclectic architecture best describes the structure.

In 1984, it received the precursor status of a cultural asset by being designated as a historic-artistic monument.