late 14c., "olden times," from Old French antiquitet (11c.; Modern French antiquité) "olden times; great age; old age," from Latin antiquitatem (nominative antiquitas) "ancient times, antiquity, venerableness," noun of quality from stem of antiquus "ancient, of olden times; long in existence" (see antique (adj.)). Specific reference to ancient Greece and Rome is from mid-15c.; meaning "quality of being old" is from about the same time. Antiquities "relics of ancient days" is from 1510s.
To be ignorant of all antiquity is a mutilation of the human mind [I. Disraeli, "Amenities of Literature"]