Kiek in de Kök Museum and Bastion Tunnels, Tallinn.

“Kiek in de Kök (Low German: Peek into the Kitchen) is an artillery tower in Tallinn, Estonia, built in 1475. It gained the name Kiek in de Kök from the ability of tower occupants to see into kitchens of nearby houses. The tower is 38 m (125 ft) high and has walls 4 m (13 ft) thick. Cannonballs dating back to 1577 are still embedded in its outer walls.”