Just reading through the monument / pillar website and found the following:
The lone Red Seat in the South Ward signifies the Red Bulls’ first goal scored at Red Bull Arena by Joel Lindpere. The seat is housed specifically in Section 101, Row 11, Seat 20. Section 101 represents the arena’s first game, Row 11 marks the minute of the game in which the goal was scored, and Seat 20 identifies the goal scorer, No. 20, Joel Lindpere.
On Nov. 8, 2015, prior to the Red Bulls' playoff match against D.C. United, the club unveiled a special addition to the Red Seat. Following the passing of Empire Supporters Club member Mike Vallo, the Red Seat's No. 20 was replaced by the initials "MV" to honor the memory of Vallo, who called section 101 at Red Bull Arena home.
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The single greatest gesture this franchise has ever done.