Английский Этимологический словарь - gallery

- early 15c., from M.Fr. galerie "a long portico," from M.L. galeria, of uncertain origin, perhaps alteration of galilea "church porch," probably from L. Galilaea "Galilee," the northernmost region of Palestine; church porches so called from being at the far end of the church. Sense of "building to house art" first recorded 1591; that of "people who occupy a (theater) gallery" (contrasted with "gentlemen of the pit") first by Lovelace, 1649, hence to play to the gallery.