Jewish Tombstone in Caltabellotta

In Caltabellotta, walled into the facade of a building, there is a Jewish Sepulchral Plaque dating back to the 15th century.
The building located in via IV Novembre has a plaque with Hebrew inscriptions above the main door, between the arch of the door on the ground floor and the landing of the balcony above. The presence of this plaque and the Hebrew inscriptions are consistent with the fact that in Caltabellotta there was a synagogue near the building in the 15th century.
It is believed that the plaque is walled up in the building only for an aesthetic reason, it is in fact placed upside down.
The inscription on the tombstone reads O God, keep him, have mercy on him. Isaac left the world in the year 1479.