Boreum was a Byzantine fortress in modern Libya, now called Bu Grada.
The last city of Pentapolis towards the west is named Boreium. Here the mountains press close upon one another, and thus forming a barrier by their crowding, effectively close the entrance to the enemy. This city, which had been without a wall, the Emperor [Emperor Justinian] enclosed with very strong defences, thus making it as safe as possible for the future, together with the whole country round about it 1.
See:
- Procopius De Aedificiis, VI, 1, 11-13 - http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Procopius/Buildings/6*.html
References
- ↑Procopius De Aedificiis, VI, 1, 11-13