Horrea were frequently built with very thick walls (as much as 1 m / 3 ft thick) to reduce the danger of fire, and the windows were always narrow and placed high up on the wall to deter theft.
Horreum-urile au fost construite frecvent cu ziduri foarte groase (până la 1 m) reduce pericolul de incendiu iar ferestrele au fost întotdeauna înguste și plasate mai sus pentru a descuraja furtul.