The Rotas Square (or Sator Square) is a word square containing a Latin palindrome. By repositioning the letters around the central letter ?, a Greek cross can be made that reads Pater Noster (Latin for 'Our Father', the first two words of the Lord's Prayer) both vertically and horizontally. The remaining letters ??two each of A and O ??can be taken to represent the concept of Alpha and Omega, a reference in Christianity to the omnipresence of God.

The square was likely used as a covert symbol for early Christians to express their presence to each other.