Yoma, Chapter Six, Mishnah Four
This mishnah describes the goat leaving the Temple.
1) And they made a ramp for him because of the Babylonians, who would pull its hair, shouting to it: Take it and go out, take it and go out.
2) Some of the important people of Jerusalem used to go with him up to the first booth.
a) There were ten booths from Jerusalem to Tzuk [a distance of] ninety ris, seven and a half of which make a mil.
Section one: The mishnah describes a ramp on which the goat would leave the Temple courtyard and make his way out of Jerusalem. They had to make this ramp because Babylonians on a pilgrimage to Jerusalem would pull at the hair of the person appointed to lead the goat out of the city in an attempt to hurry him on his way. The ramp kept the priest leading the goat at a safe distance from the rowdy pilgrims.
Section two: The mishnah mentions ten booths that were set up on the way from Jerusalem to Tzuk, the rock where the goats journey will end (as we will see below). On the way to Tzuk, which was ninety ris from Jerusalem (equivalent to 90 mil, or in our terms about 90 km) there were ten booths (sukkot). The important people from Jerusalem would accompany the goat to the first sukkah, and from that sukkah others would accompany it to the next sukkah and so on until it reached Tzuk. Between each sukkah was one mil, equivalent to two thousand cubits, the limit which one may walk on Shabbat. Between the last sukkah and Tzuk were two mil.