Argyre Planitia (Mars)

Classical albedo feature name; "First Silver Land", a mythical island in Greek mythology

Argyre Planitia is a plain located within the impact basin Argyre in the southern highlands of Mars. Its name comes from a map produced by Giovanni Schiaparelli in 1877; it refers to Argyre, a mythical island of silver in Greek mythology. Argyre is centered at 49.7°S 316.0°E / -49.7; 316.0 and lies. The basin is approximately 1,800 km below the surrounding plains; it is the second deepest impact basin on Mars after Hellas. (wikipedia entry)

A planitia is a low plain. On Mars they are named after the nearest named albedo feature on the Schiaparelli or Antoniadi maps.