The Mishna on today’s daf discusses what would be included when someone sells a city. According to the Mishna such a sale would include all permanent structures, like houses, water holes, bathhouses and dovecotes, olive presses and gardens. It would not include any moveable objects, unless that was specifically agreed upon. If, in fact, the agreement was that everything in the city was included, then animals and slaves in the city would be included in the sale, as well.
From this Mishna, as well as other places in the Talmud it is clear that aside from large cities that were public property, there also were privately owned cities. Such places were large tracts of land that included houses and other structures, all of which belonged to a single individual. Those people who lived on the land were his tenants while all the permanent, fixed structures, belonged to him, and he could choose to sell them to another.
The Mishna concludes with the ruling of Rabban Shimon ben Gamliel, who says that in all circumstances the santar of the city would be included in the sale, even if it wasn’t specified.
Two explanations of the concept of “santar of the city” are put forward in the Gemara. One suggestion is that it is the person who watches the city; the other is that it is the fields that surround the city.
Most of the rishonim understand the first suggestion – that it refers to the person who watches the city – as meaning the person who knows the divisions of the city, the different parcels of land, how it is taxed, and so forth. Since it is impossible for the city to continue to function without the person who has all of this information, Rabban Shimon ben Gamliel rules that he must be included in the sale. Others suggest that this is the guard who knows the layout of the city, its strengths and weaknesses, and how it must be protected.