How did the lord of a large town keep track of who owned what house ? In skyrim there is a quest where you just steal the deed to a house and it becomes yours, how realistic would that be ? Was a deed really the only thing standing in tour way of homelessness ?
To start off with, here's a previous answer I wrote about buying medieval houses in general, which might also be helpful:
How did someone go about buying a house in medieval times?
I should say that I really only know about this for the specific example of 13th-century crusader Jerusalem/Acre (and maybe Cyprus). Since their customs and laws for things like urban housing contracts came from southern France and Italy, I would assume the same ideas also applied there, but I’m not sure I have any specific examples for those places.
So first of all, imagine you’re a fairly well-off merchant or trader or craftsman (a "burgess") in Acre or another crusader city along the Mediterranean coast. You might be French or Italian, or you might have been born in the east. Your neighbours are fellow native-born Latins, or European merchants, as well as native Christians (Greek, Syrian, Armenian, etc). They might have some Muslim slaves, and there might be some free Muslims living there too, and maybe some Jews. It’s a pretty cosmopolitan place.
There are knights and nobles around, and they own a lot of property, but you might not interact much with them. Most of their land was out in the countryside, not in the city. The big landowners are the military orders (Templars and Hospitallers), and the church (complicated in Acre because the Patriarch of Jerusalem lived there in exile, competing with the Bishop of Acre). You might be lucky enough to own a bit of land yourself, if you were wealthy enough - maybe a small shop with one or more residential storeys on top of it. But most likely you’d be renting a house from the church or the military orders.
From a legal point of view, you’ve got a few avenues to work with. There’s the High Court for the aristocrats, but as a non-noble you don’t need to go there. For everyone else there’s the Burgess Court, which had jurisdiction over several other courts (the market court in the harbour, and the religious courts for all the other non-Latin Catholic communities). There are also church courts but the church could work through the burgess court if they were renting out a house. Depending on the circumstances, you might be able to skip the burgess court entirely and conduct your transaction through an Italian notary.
Whether you do business with the court or with a notary, they’ll draw up a deed, which is essentially the same as a house deed today, at least in the essentials. It’ll say who owns the house, who’s renting it, the amount of term of the rent, whether the renter can sublet it, etc. If you’re buying property you could have a mortgage, or my favourite medieval legal nuance, the opposite of a mortgage, a vifgage!
The burgess court produced a document for you and a copy for its own records, and it may have also kept a register of all court transactions, so you could go back and check your copy against the register. Even if/when it didn’t have a register it must have had some way to confirm that your deed was valid. A common way of doing this in the Middle Ages (everywhere, not just the crusader states) was to cut the deed in two, so the court had one piece and you had the other. This is called a chirograph - the two pieces fit together uniquely so you couldn’t defraud the court.
Notaries would do the same thing, keep one copy and give you the other or make a chirograph. Apparently it was much faster and simpler to go to a notary. There was only one burgess court in a city so there was probably a big backlog. You had to hire a lawyer and speak certain formulaic phrases in a precise way in a precise order…it was probably a pain in the butt. But meantime the profession of notaries had developed in Italy and had spread to the crusader states through the Italian merchant communities. There was a bit of opposition to them at first (they’re not the court, where do they get their authority from?) but it was so much simpler to pay a few bezants and get a notary to write up a deed for you, which everyone else was willing to recognize because they didn’t want to deal with all the court procedures either.
So, at least in the crusader cities in the 13th century, the actual lord of the town (the viscount) didn’t need to keep any records because the legal courts did it for them. It’s not realistic to just steal someone’s deed - a thief might have the piece of paper that matches the one in the court register or the notary’s records, but as the actual owner/renter, you could easily sue the imposter in court and call witnesses to testify for you. They’d have to somehow prove they were the legitimate deed-holder. It wasn't not completely lawless - if anything it was the opposite, there was so much law, and the crusaders loved arguing about it in court. It would be pretty difficult to get away with just stealing a deed.
This is a pretty dry topic (even for me) and I’m not sure there’s really a basic overview…for books, the best places to look are:
Marwan Nader, Burgesses and Burgess Law in the Latin Kingdoms of Jerusalem and Cyprus (1099-1325) (Ashgate, 2006)
Joshua Prawer, Crusader Institutions (Oxford University Press, 1980, repr. Sandpiper Books, 1998)
And the most recent book about this...even though it's in German which probably doesn't help...
Hans E. Mayer, Von der Cour des Bourgeois zum öffentlichen Notariat: Die freiwillige Gerichtsbarkeit in den Kreuzfahrerstaaten (Harrassowitz Verlag, 2016)
Pre-Conquest, land in England was typically split between folc-land, that is, land the ownership of which is known through common law or continual practice; and boc-land, the ownership if which is specified by charter, will or other literate record. Commonly, English kings would re-issue charters signed by their predecessors either as a matter of practicality (in that the original had become lost or degraded), or simply to reaffirm a longstanding support for a particular institution or house.
Post-Conquest, land tenure rapidly becomes a matter of "copy-land", especially at the lower end of the scale dealing with individual tenancies or small settlements. Land-ownership and tenancies within a parish or manor would be collated in a centralised record for ease of bureaucratic control, from which individual tenants would be provided a copy of their specific lease terms.