Lugo sits in the northwest corner of a broad and fertile alluvial plain which is watered by several rivers.
The Rio Miño flows past the west side of the settlement, which is on a high spot of ground formed by a prehistoric gravel bar. The community (or Citiano) was surrounded by a low earthen embankment, topped by a stout, drystone wall. At it's peak, This wall was nearly two kilometers (1.2 miles) in length and enclosed a space of roughly 35 hectares (90 acres). Though there has been little archaeological work done on the Celtic period, preliminary surveys suggest the population may have been as great as 10,000. The houses (castros) were round and built of limestone blocks which were carefully fitted together to form a tight wall almost two feet in thickness. The roofs were thatch, supported on a framework of wooden poles.

This was the home of the Arevaci Tribe, one of the first groups of Celts to move out of Gaul, sometime around 600 BC. Rather than driving out the native Iberians, they mingled and intermarried, creating the Celtiberians. The Iberians were the remnants of a migration of Neolithic peoples from Libya, who arrived in the 5th millennium BC. When the Romans arrived around 20 BC, they found a thriving agricultural community. They also found strong resistance to their intrusion, and the Cantabrian Wars were fought. The Village of Lugo was leveled and a Roman fort was built atop the ruins. The Roman Walls are still in good condition today, a source of pride for the modern-day inhabitants (Lugueses or Lucenses) of the city.

Today, Lugo has returned to a modern version of what it was before the Romans came… a bustling agricultural center in the midst of a broad and fertile valley. The area is well watered by the Rio Miño, which has its source in the mountains to the north.