Algeron IV

From Memory Alpha, the free Star Trek reference.

Algeron IV, a planet of the Algeron system, hosted the peace conference which culminated in the Treaty of Algeron in 2311. (TNG: "The Pegasus")

Decades later, it was the site for the next mission assignment of the USS Enterprise-D after a brief layover at Relva VII. (TNG: "Coming of Age")