Wikipedia
The Graecostasis was a platform in the Comitium near the Roman forum, located to the west of the Rostra. The name refers to the Greek ambassadors for whom the platform was originally built after the Roman Republic conquered Greece. Placed at the southwest end of the Comitium, the platform was the designated spot for all representatives of foreign nations and dignitaries from the republic and empire's domain.
Visiting outsiders were not permitted within the Senate House or Curia and instead may have stood on this platform while waiting to meet with senators or to hear orations from the Rostra to its east side. Although one scholar has disputed this interpretation and argues that it may have served as a viewing platform for entertainment.