Beatlemania was a musical that ran for a few years in the late 70s. It was essentially a tribute to the Beatles, and consisted mostly of music from the Beatles throughout the decades.
This tee appears to be from the 70s, perhaps purchased at musical itself. It is tagged large on a Nu West Sportwear tag, but fits small.
Measurements are:
pit to pit - 17”
length - 26.5”