Robur

ROBURA mmianus Marcellinus (Ammian. 30.3) mentions a fortress named Robur, which Valentinian I., A.D. 374, built near Basilia (Basle) on the Rhine in Switzerland. Schoepflin guessed that Robur was on the site of the cathedral of Basle, but the words of Ammianus do not give much support to this conjecture: Prope Basiliam, quod appellant accolae Robur.Others have made other guesses.
[G.L]