Apianus is a lunar impact crater that is located on the rugged south-central highlands of the Moon. It is located to the northeast of Aliacensis crater, and to the northwest of the Poisson crater remnant. The worn crater Krusenstern is attached to the west-northwestern rim.

The outer wall of Apianus crater has been worn and eroded by subsequent impacts, and a pair of small craterlets overlay the rim to the southeast and northeast. The craterlet on the southeast rim, 'Apianus B', is a member of a cluster of co-joined craterlets that includes 'Apianus T' and 'Apianus U'. The interior floor is relatively smooth and lacks a central peak, although the surface appears somewhat convex. Only a few tiny craterlets mark the surface.

Satellite craters

By convention these features are identified on Lunar maps by placing the letter on the side of the crater mid-point that is closest to Apianus crater.