Prime Minister Syed Yusuf Raza Gilani on Saturday said that the passage of amendments to restore 1973 Constitution in its original without having simple majority was the biggest achievement of his government. Talking to newsmen here at Prime Minister House, the Prime Minister said the restoration of 1973 Constitution was a challenging task when he took over as the chief executive four years ago. The government accomplished the task with the support of other political parties by passing three constitutional amendments, he added.