Bava Basra, Chapter 4, Mishnah 7. This Mishnah parallels the previous mishnayos we learned in the chapter, which dealt with one who sells a house or one who sells a courtyard. Now the Mishnah deals with the sale of an entire city - an entire village that is completely owned by one person, and he is packing his belongings and moving to another place.
The same logic that was suggested above, that a courtyard includes more than a house, is true here a fortiori (kal vachomer). Since the person is moving to a distant place, he is likely to leave things behind, because it is a great bother to move all the furniture and items. When moving to a new city, the tendency to leave things behind is even greater.
The language of the Mishnah:
"Hamocher es ha'ir" - A person who agreed to sell the city without specifying what is included in the sale. (When it says 'city' here, the intention is a small village of a few hundred residents, and not a city in its modern sense.) And these are the things included in the sale:
"Machar batim" - The houses in the city are included in the sale.
"Boros, shichin, ume'aros" - The water cisterns and water storage facilities, the long, the narrow, and the square ones.
"Merchatza'os" - The bathhouses, which every city needs.
"Veshovchos" - The dovecotes, where doves and pigeons are raised, and since this is a common thing in a city, it is also included.
"Beis habadim" - The olive presses, which were a standard thing in every city. In every ruin throughout the Land of Israel, olive presses and wine presses and the like are found.
"Uveis hashlachin" - According to the Bartenura, the intention here is not irrigated fields as is the usual meaning of the term, but rather irrigated gardens: gardens, parks, and perhaps orchards. We are speaking about areas inside the city and not fields outside of it.
"Aval lo es hametaltelin" - The movable items inside the city are not included in the sale, and even the key to the gate is included in this. All those things - a storehouse of food, of clothing, or of money - are not sold.
"Uvizman she'amar lo hi vechol mah shebesochah" - If the seller specified that he is selling the city and everything that is inside it, then 'everything that is inside it' means literally that. "Afilu hayu bah behemah va'avadim" - Not only the storehouses of food, clothing, and money are included, but even things that walk on their own power, like animals and slaves. Everything that is found there and belongs to him is handed over in the sale, because this is a package deal, "harei kulan mechorin" - they are all sold.
"Rabban Shimon ben Gamliel omer: hamocher es ha'ir machar es hasantar" - Rabban Shimon ben Gamliel says: One who sells the city has sold the santar:
Rabban Shimon ben Gamliel adds that the santar is also included in the sale, and this law applies even when the seller did not say 'and everything that is inside it' - the santar goes with the city.
What is a santar? There are many approaches in explaining it:
According to the Bartenura, this refers to a slave whose job is to serve as the city guard.
The Rashbam explains that he is a sort of city surveyor: a person responsible for knowing what belongs to whom and where the boundaries of people's properties end. He oversees that there will be no trespassing on others' properties or taking over their assets, and because this is an essential role, he is also included in the sale.
There are those who learn that the intention is the planted areas, like the fields surrounding the city.
Halachah: The halachah does not follow Rabban Shimon ben Gamliel regarding the santar, since this is an individual opinion. All the other details depend, like all the mishnayos in the chapter, on what is generally understood by people at that time and in that place. And it is hard to imagine that this matter would be practically relevant nowadays.