Jesus was not crucified on a hill, but on a rock that was shaped in the form of a man's skull at a place called Golgotha. The term "Golgotha" meant "a place of the skull" as written in the Gospel of Matthew. In Latin, this place is referred to as "Calvary."
The crucifixion took place outside the city because Jewish laws did not permit crucifixion inside the city. Most executions in the Roman empire were done publicly to allow mockery from crowds of townspeople. The place of Jesus' crucifixion was elevated to allow people to see him from a distance. In contemporary times, the exact site of the crucifixion of Jesus is still a debated topic.