I barely remember some of one of my dreams from last night, which took place in a large windowless multi-floor/story building that was like a combination of an apartment/dorm/church/hospital/mansion/building, and I remember being on one of the upper floors.
The building was dimly lit and zombies would attack and/or we would come across them in controlled waves/encounters, like in the video games Left 4 Dead & Left 4 Dead 2, where the zombie encounters vary depending on the situation of the gamer(s).
Melee and/or ranged weapons could be found in various areas around the building, and about thirty or more people were scattered around the building; and sometimes I would come across other people, and sometimes we would work together until we would get separated after a zombie attack.