Williams is the remnant of a lunar

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 crater

Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

 that lies to the south of the prominent crater Hercules

Hercules (crater)

Hercules is a prominent crater located in the northwest part of the Moon, to the east of the crater Atlas. It lies along the east edge of a southward extension in the Mare Frigoris. To the west across the mare is Bürg. To the south is the ruined crater Williams.The interior walls of Hercules have...

, in the northeastern part of the Moon

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

. The southern rim borders the Lacus Somniorum

Lacus Somniorum

Lacus Somniorum is a plain located in the northeastern part of the Moon's near side. It is located at selenographic coordinates 38.0° N, 29.2° E, and has a diameter of 384 kilometers...

, a small lunar mare

Lunar mare

The lunar maria are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for "seas", by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich compositions, and...

 that extends to the south and west. To the southwest is the sharp-rimmed crater Grove

Grove (crater)

Grove is a small lunar impact crater that lies in the northern part of the Lacus Somniorum. It is located to the southeast of the crater remnant Mason. Grove is a relatively circular crater formation with a simple, sharp-edged rim. The unconsolidated material along the inner wall has slumped down...

.

Little remains of the original crater, besides a low curving ridge. The rim has been nearly destroyed along the northwest face, leaving only a few ridges in the surface. The remainder forms an irregular horseshoe, with the western part attached to a series of ridges leading to the west. The interior floor has been resurfaced by basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

ic lava

Lava

Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

, forming a flat, nearly featureless surface that is marked only by a pair of tiny craters near the northeast rim.

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 Williams.

Williams	Latitude	Longitude	Diameter
F	43.5° N	38.2° E	7 km
M	41.2° N	38.8° E	5 km
N	42.1° N	36.3° E	5 km
R	42.5° N	38.3° E	4 km