Conversation so far:
What are some of Groban's famous performances?
In June 2007, Groban recorded a Christmas album in London with the London Symphony Orchestra and the Magdalen College Choir.
what songs did he sing?
"My Country 'Tis of Thee.
Has he ever performed with other famous singers?
"My Country 'Tis of Thee" in duet with Heather Headley.

Question: What awards ceremonies if any did he perform at?
Self-contained rewrite: What awards ceremonies if any did Groban perform at?