The Roundabout Theatre Company honored Stephen Sondheim on Monday, March 22, his 80th birthday, with the Sondheim 80 Gala. The evening began with a special performance of the Roundabout's Sondheim on Sondheim, and Sondheim was greeted by the cast, including stars Euan Morton, Vanessa Williams, Barbara Cook, and Tom Wopat. A special announcement was made after the curtain call that the Roundabout is renaming Henry Miller's Theatre the Stephen Sondheim Theatre.

Five-time Tony Award winner Angela Lansbury, who is currently starring on Broadway in A Little Night Music attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Academy Award winner Lauren Bacall attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Tony Award winner Michael Cerveris and Emmy Award winner Alec Baldwin attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Tony Award winner Jane Krakowski, who starred in the Roundabout's revival of Stephen Sondheim's Company, attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Tony Award winner Christine Baranski, who currently stars on CBS' The Good Wife, attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Tony Award nominee Kelli O'Hara, who will appear with the New York Pops at Carnegie Hall on April 16, attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Tony Award winner Donna Murphy, who will star in the upcoming City Center Encores! production of Stephen Sondheim's Anyone Can Whistle, attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Tony Award nominee Victor Garber, who recently starred in the Roundabout's revival of Noel Coward's Present Laughter, attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Joanna Gleason, who won the Tony Award for the original Broadway production of Stephen Sondheim's Into the Woods, attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Aaron Lazar, who is starring in the current Broadway production of Stephen Sondheim's A Little Night Music, and wife LeAnn attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Charlotte Moore and John McMartin, who starred in the original Broadway production of Stephen Sondheim's Follies, attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Melissa Errico, who is currently starring in the Irish Repertory Theatre's production of Candida, attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Tony Award nominee Daniel Reichard attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.

Tony Award winner Lin-Manuel Miranda attended the Roundabout Theatre Company's Sondheim 80 Gala at Studio 54 on Monday, March 22.