LOIV 101 H3 Oppolzer is the "ruined" enclosure to the left of center. To its southeast is the similar, but larger (52 km) Réaumur. The larger of the two craters on the floor of Oppolzer is 3-km Oppolzer K. Just to the north of Oppolzer, in Sinus Medii, is 3-km Oppolzer A, the named feature closest to the center of the lunar coordinate grid. A portion of Rima Oppolzer is also visible, cutting across the floor and north rim of Réaumur.