Britney Spears celebrated her 27th birthday Tuesday on Good Morning America in New York City.

Spears, who was dressed as a ringmaster, entered New York’s Lincoln Center atop a giant cage to perform “Circus,” alongside clowns, jugglers and performers dressed as circus animals. She also performed “Womanizer.”

Spears also had a special announcement – revealing the dates of her upcoming world tour, which kicks off in New Orleans March 3.

She was then presented with a six-tier cake by Buddy Velastro of Carlo’s Bakery.

Before being presented with the cake, Hugh Jackman sang her “Happy Birthday” in a pre-taped message; Reese Witherspoon also wished her the best and Taylor Swift joked that she cried when she met Spears at the MTV Video Music Awards this year.

Spears looked really surprised and touched by their greetings.

Sawyer then gave Spears a hug.

Inside the tent: Her parents, Lynne and Jamie Spears, her brother, Brian, and her two young sons, Preston and Jayden, who held a sign that read “Happy Birthday, Britney!”

Spears will continue her birthday celebrations tonight at NYC hot spot Tenjune.