Lewis & Short

Septizōnĭum (Septemzōdĭum), ii, n. [septem-zona].

  1. I. A large building in Rome in the twelfth region, prob. seven stories in height, Suet. Tit. 2 init.
  2. II. A monument of the emperor Septimius Severus, in the tenth region, Spart. Sev. 19; 35.
  3. III. A building of M. Aurelius Antoninus, Amm. 15, 7, 3 (others consider II. and III. to have been the same building).
  4. IV. The seven planets, Commod. 7 and 19.