When looking at the ruins of ancient cities in many places around the world, but to be simple, specifically Uruk, the “units” which make up people’s houses seems to be bunched together, sharing walls and sometimes having doors between them. How did ownership of these buildings work? We’re there owners for the whole “block” who rented these spaces out, or were they owned like townhouses? If so we’re there any organizations akin to home-owners associates or laws governing where one of these buildings started and where one ended?
And as an tangential question, would “public” buildings like temples and shops be owned by those who worked there, or by the King, or something else?
Just as a disclaimer: Uruk is actually quite a difficult example because less than 5% of the area of the city has been excavated and we know relatively little about the residential architecture, and Uruk also has a very long settlement history (more than 4000 years) and there were significant changes to the social and economic organisation during this time. So my answer is also based on information from different Mesopotamian cities and different time periods.
In general, the standard (Southern) Mesopotamian house consisted of a central courtyard surrounded by rooms (an example of the basic type is here). There was a maximum of two storeys (you cannot really build any higher in mudbrick), so these were more like townhouses (rather than, say, apartment blocks), and yes, they would in most cases share the walls with the house next door. In general, the rule seems to have been one house for one household or family unit (which could just be a core family of parents and children, but also be a larger unit including other family members and servants/slaves) and for the most part the houses were owned by the families living in them, although there are also examples where institutions may possibly have provided housing for their staff.
Depending on the size of your household, you might need a larger or smaller house and there are different ways in which house size can change. A house owner could, for example, purchase rooms or sections of a neighbour's house and incorporate them into his own house (doorways are relatively easily changed in mudbrick architecture) – we even have cases of buildings expanding into public areas or streets, but it seems likely that only certain people were allowed to do that. There are also some problems arising from the division of inheritance: generally, in Mesopotamian law, all the sons are due a share of the inheritance, not just the oldest son, so sometimes the house had to be divided up into smaller units to accommodate the different sons' inheritance. These developments – over several generations – were the source for some of the strange floor plans that we find in ancient Mesopotamian cities (one example where houses are highlighted, albeit from Ur, not Uruk is here). Elizabeth Stone has in her 1981 article managed to connect the property transactions found in the texts with alterations in the excavated houses in Nippur, but complementary textual and archaeological data like that is unfortunately very rare.
I am not quite sure what you mean by sharing a door. Generally, one house had one main entrance (and maybe a back entrance), so all the rooms that could be reached from that entrance form one house for one family unit.
Regarding the Homeowners' Association: there was (at least in some time periods) a local government (or local assembly) that would settle smaller disputes in the different city wards, and neighbourhood disputes would likely end up being settled there.
The temples were their own economic units (or 'households') – they owned their own land and were also engaged in the production of goods, particularly textiles, and employed several thousand people. Some of the smaller shrines and chapels in the residential neighbourhoods may have been maintained by the local population (or by the local assemblies), but we are not quite sure. Shops would for the most part be owned by private individuals.
Some literature:
E. F. Henrickson (1981): 'Non-Religious Residential Settlement Patterning in the Late Early Dynastic of the Diyala Region', Mesopotamia 16, 43-79 + appendix.
M. van de Mieroop (1997): The Ancient Mesopotamian City. Oxford University Press. (especially Chapters 5 Social Organisation and 6 Urban Government: King, Citizens, and Officials).
E. C. Stone (1981): 'Texts, Architecture and Ethnographic Analogy. Patterns of Residence in Old Babylonian Nippur', Iraq 43, s. 19-33.
