- Arnaldus, de Villanova, -13111
- Arrighi family1
- Arrigucci family1
- Arrigucci, Caterina1
- Arrigucci, Luigi1
- Art1
- Arte della lana (Guild : Florence, Italy)1
- Asceticism--Early church1
- Assumption of the Blessed Virgin Mary1
- Astrology, Hebrew1
- Astronomical instruments1
- Astronomy, Ancient1
- Astronomy, Greek1
- Attila, -4531
- Augsburg Confession1
- Augustus, Emperor of Rome, 63 B.C.-14 A.D.1
- Aurispa, Giovanni, approximately 1376-14591
- Austria--Lambach (Upper Austria)1
- Austrian1
- Aveiro, Gabriel de Lencastre, Duque de, 1667-17451