The Bank is where the town stores all the useful items to be shared by the community.
Items are found in the World Beyond by entering a controlled territory and scavenging for resources. Some item combinations can create new items. 
Defence Defence objects placed in the bank provide protection for the whole town. You can take five items before you are locked out of the bank for 15 minutes, taking an extra ration at the well counts towards this limit (does your daily ration?).
Resources
Armoury
Containers and Boxes
Defences
Food
Furniture
Pharmacy
Miscellaneous