Taucheira: Greek port in the Cyrenaica, also known as Arsinoe.
The barracks of the Byzantine forces in Taucheira were in the center of the city, on the southeastern side of the main road. As you can see on the photo, it was a square building with towers on the corners. It was built in the seventh century, perhaps when Egypt was briefly occupied by the Sasanian troops of king Khusrau II (in 619). The old city walls were of course also part of the city's defense.
Because it was, for that age, a modern fort, Byzantine commander Apollonius was able to to hold out until 645 when the Arab forces invaded the Cyrenaica in 641.