Nili Fossae is a group of large, concentric grabens on Mars, in the Syrtis Major quadrangle.

They have been eroded and partly filled in by sediments and clay-rich ejecta from a nearby giant impact crater, the Isidis basin.

[2] In December 2008, NASA's Mars Reconnaissance Orbiter found that rocks at Nili Fossae contain carbonate minerals, a geologically significant discovery.

[9] Nili Fossae trough is thought to have resulted from the impact that formed the nearby Isidis basin.

[citation needed] Although not among the last finalists, in September 2015 it was selected as a potential landing site for the Mars 2020 rover, which will use the same design as Curiosity, but with a different payload focused on astrobiology.