A 1,800-km impact basin, ringed by mountains and frosted with ice.
Argyre Planitia is one of the largest and best-preserved impact basins on Mars, roughly 1,800 km across. Ringed by rugged mountain arcs and often coated with seasonal frost, it lies deep in the southern highlands and may once have held a lake or ice deposits.
Claim your plot here →Argyre formed in a colossal impact early in Martian history, blasting out a basin nearly 1,800 km wide and throwing up encircling mountain ranges — the Charitum and Nereidum Montes — that still rise sharply around its rim. Its floor is one of the more pristine large basins on the planet, less buried than others by later lava and sediment.
Evidence suggests Argyre may have hosted standing water or ice, fed by channels draining from the surrounding highlands, and its floor and rim preserve glacial and possible lake features. Because it lies far south, the basin frequently catches seasonal frosts and hazes, making it one of the more visually striking regions when imaged from orbit.
The runner-up to Hellas in size, but often better preserved and framed by dramatic mountain rims.
No impact basin on Earth survives at this scale — Argyre could hold whole countries within its rim.