antika

1. classical antiquity; antiquity
   Ovaj hram potiče iz antike. — This temple dates back to antiquity.
   Na fakultetu je proučavala filozofiju antike. — At university she studied the philosophy of antiquity.
2. colloq. (of an object) antique; ancient thing
   Ovaj tvoj telefon je prava antika. — That phone of yours is a real antique.

For the period it's usually used as u antici "in antiquity".