It seems that this Skladiště in slumy of the Chrámová čtvrť has gotten a lot of use through the years.
The warehouse is where Vincent conducts his little "sting operation" on the local Salamandra he's recently identified. When Geralt gets out of prison, the captain suggests that the witcher stay way from the warehouse in the slums, especially around midnight. A witcher's sword would not be needed then. Indeed!