Historical Association of Las Piedras believes that the process of foundation of the current Las Piedras started a March 8, 1744, when Luis Sosa Mascarene received as donation a land of one square league. The first name of the present city was San Isidro Labrador de Las Piedras and from 1925 is recognized as a city.
Its name derives from an old area have been quarrying stone.
In the city an obelisk commemorating one of the most important victories of the army of Artigas on Spanish troops stands. On 18 May 1811 the eastern army defeated the Spanish troops under the command of Posadas in the so-called Battle of Las Piedras.