878. Square, Round and Triangular Cities

Shabbos 28:6

If a city is a rectangle or a square, since it has four right angles, we leave it "as is" and simply measure 2,000 cubits in each direction on each of the four sides. If a city is a circle, we imagine that it is surrounded by a square. We then measure 2,000 cubits in every direction from the sides of that square. In this way, the residents of the city enjoy the benefit of the extra area in the corners of the square.

Shabbos 28:7

Similarly, if a city is triangular or has many sides, we imagine a square around it. We then measure 2,000 cubits from the sides of that square. When we imagine a square around a city, it is positioned according to the compass directions; each side of the square aligns with one of the four directions and a straight line extends north-south or east-west.