Complex sentence: The Main Stand had its first renovation in 2005--06 and after a significant modernization project, it was opened on 23 April 2006 with a roof over 1,504 seats.
Split into simpler sentences: The Main Stand had its first renovation in 2005--2006. After undergoing a significant modernization process, it was opened on April 23,2006, adding a roof and over 1,504 seats.