Pomerium or pomoerium (literally “beyond the mountains”) was a line of a sacred character delimiting the boundaries of the city of Rome. In legal terms, Rome functioned as an institution only within these borders, beyond which there were simply lands (ager) belonging to Rome.
Pomerium demarcated the range of civil and military power, and the military empire did not exist within its borders. Hence, in the uncertain times of the republic’s decline, chieftains often convened the Senate in the temples of the Field of Mars, which was already beyond pomerium. It was forbidden to enter the city with weapons, except for triumphs. Moreover, it was not allowed to bury the dead within the pomerium.
Although Julius Caesar received permission from the Senate to bury his ashes within the sacred border, he eventually rested in the family tomb. It is worth adding that Caesar was murdered in the Pompey Theater, which was located outside the holy city limits. As a result, senators (armed) who could not cross pomerium appeared at a meeting with Caesar and could participate in the plot for the life of the dictator. The only ruler buried within pomerium was Emperor Trajan in 117 CE – was buried at the foot of his column.