Many people know that driving a car on Shabbat is prohibited, but you might be surprised to find that on Shabbat, even walking has its limits. It’s 2,000 cubits to be exact (about 3,000 feet). But this measurement’s starting line starts outside city limits—within the perimeters of a city, one can walk any distance. Since many cities are surrounded by adjoining cities, or suburbs that blend endlessly into each other, circumstances where this law applies are somewhat limited. The issue of techum Shabbat is definitely applicable in areas like the Catskill Mountains of New York. In order to demarcate the line of this boundary – known in Hebrew as techum Shabbat – a sign is often erected to that effect.
This past July a man walking his dog in the Timrat area of Lower Galilee in Israel, noticed a large rock with some faint lines etched on it. Upon closer inspection he could make out three letters. At first he thought they spelled the word ש כ ח - forget, although he was puzzled why someone would carve this word on a stone. After discussing it with a neighbor, they concluded it probably said ש ב ת - Shabbat.
The two men returned to the rock, eager to see if they were right. They filled in the carved letters with soil, and saw this:
Who put this stone here, why, and when?
 It should be noted that the municipal designations of where a city begins or ends has no bearings on this Halachah. Halachah designates any contiguously populated area as a single city, and a large unpopulated area, even if according to Google Maps it is plunk in the middle of a city, is considered outside the city’s borders. (The specifics of how many residences are needed in order to constitute a city, and what type of structures qualify as residences, are very complex. A rabbi should be consulted in case of actual question.)