Eruvin 56: How to Square a City

Cities that have ascents and descents within it take a toll on their residents. And: The rest of the day is as challenging as we've seen. That is, one way of measuring the location of your city's edges to determine the city limits is by using the constellations... And the daf addresses how to do so. Also: Adding the extra space to make the city shapes smooth is *a lot* of extra space. Note that the cities of the leviim - which were also cities of refuge - included extra space, even beyond the add-on to make a smooth shape.