The structure in this film is derived from a single tower of the Maunsell army forts built in groups of seven to defend the Thames Estuary & River Thames ports during WWII. The Red Sands group & 6 of the 7 Shivering Sands towers remain to this very day.
Most of the inside scenes were filmed in Tallinn, Linnahall. The same building, which was Kiev Opera hall in Tenet.