Theophilus (61 miles), Cyrillus and Catharina form an exceptional trio of craters. The showpiece of these three is Theophilus. Its walls reach up to 2½ miles from the flat floor. This formation is a great showpiece 5 days after new Moon. Its central mountain mass is over a mile high. The great walls are terraced and there is a 5 mile crater in the terraces on the northwest wall.
Cyrillus (59 miles) is to the southwest of Theophilus and its northeastern wall is badly damaged by its neighbor. It is not as deep as Theophilus. There are three off center mountains and a 10 mile crater on the southwestern floor.