Ptolemaeus 9.3°S, 1.9°W

Ptolomaeus is a highly distinctive, very old large crater with a diameter of 164 km. The crater wall is slightly polygonal, and because of its extreme age is heavily eroded. It rises about 2.4 km above the floor of the crater. As with many other structures of this size, a gravitational anomaly (a mascon) is measured over Ptolomaeus. The crater's floor appears flat and smooth in small telescopes, but in larger instruments a wealth of small craters and pits becomes visible. On the northeastern floor there is the prominent crater Ammonius, with a diameter of 8 km, and directly adjoining it to the north is Ptolomaeus B, a shallow, saucer-shaped depression and, even farther north, an additional, unnamed depression.

The eastern crater wall has a peak, which casts a conspicuous shadow directly across Ammonius at sunrise.

On the western part of the crater's floor and under an extremely low angle of illumination, two very shallow, circular depressions may be observed. Directly outside the northeastern wall of the crater there is a short, but very prominent, nameless chain of craters. The appearance of the floor of Ptolomaeus changes dramatically over the course of a lunation. At First and Last Quarters the crater floor appears relatively dark, but near Full Moon becomes very bright.

Davy 11.8°S, 8.1°W

Davy is a small, but conspicuous crater, 31 km in diameter. It lies west of Ptolomaeus, on the northeastern outlier of Mare Nubium. Davy A (15 km) breaches Davy's southeastern crater wall.

Directly adjoining it on the north lies the significantly larger crater Davy Y (about 60 km, 11.0 °S, 7.0 °W), on the floor of which is the well-known crater chain Catena Davy, a series of craterlets, which stretches for a distance of about 50 km.