Simplify the following text for a Grade 10 native English-speaking person.
Original: The 1976 Summer Olympics , officially known as the Games of the XXI Olympiad , were an international multi-sport event celebrated in Montreal , Quebec , Canada , in 1976 .
Simplified: <!----> The 1976 Summer Olympics , officially known as the Games of the XXI Olympiad , were held in 1976 in Montreal , Quebec , Canada .