The Al Horford era in Atlanta is over.

With it goes nine seasons of unprecedented success for the Hawks organization. Whether the run continues following several organization-altering moves over the past two days remains to be seen. If so, it will be done without the player who has been a cornerstone of the organization for nearly a decade.

Horford agreed to a maximum deal of four years, $113 million with the Celtics on Saturday. The Hawks failed to offer the four-time All-Star center a maximum deal of five years, $153 million. After imposing of Saturday evening to reach a deal, Horford will leave the team he joined as the No. 3 overall pick in the 2007 NBA Draft.

He announced his decision on social media, posting on Twitter: “Celtic Pride!!!!! with many shamrock emojis.