It is called a "centennial celebration"
It is called Centenary.
A three-hundred-year celebration is called a tricentennial.
An 150 year celebration is called a Sesquicentennial celebration
A 100 year celebration is called a centennial celebration.
60 year celebration
Centenary.
An 150 year celebration is called a Sesquicentennial celebration
55th wedding celebration is Emerald.
Centennial
Diamond Jubilee
An Emerald anniversary
It is a century or a centennial