Rome's mayor, after vowing to remove a modern museum from the banks of the Tiber, has agreed with its US architect to modify it as part of a major overhaul of the Ara Pacis complex, the two said yesterday.

Gianni Alemanno slammed the glass and marble museum - the first work of modern architecture in central Rome since the 1930s - as a "scar in the heart of the city, an act of intellectual arrogance against the citizens" when it was inaugurated in 2006.

Two years later, shortly after he was elected mayor, he vowed to remove the structure encasing the 2,000-year-old Altar of Augustan Peace, or Ara Pacis.

Now he and prominent architect Richard Meier have agreed to modifications including drastically reducing the height of a wall between an open-air space outside the museum and a busy road along the Tiber river.

The city plans to build a wide pedestrian area along the river and run the road underneath it.

"It's an improvement," Mr Meier said yesterday, adding that "the reason that wall was there has to do with traffic and noise. Once that is eliminated, the idea of opening the piazza to the river is a good one."

Mr Alemanno said yesterday: "Richard Meier gave the go-ahead, we will knock down part of the wall," the Ansa news agency reported.

The mayor's office said Mr Alemanno hopes to complete the project before the end of his term in 2013.

The delicate ancient white marble altar, built to celebrate the peace after the Emperor Augustus' triumphal return from wars in Spain and Gaul, has finely sculpted bas-reliefs.

The dictator Benito Mussolini, who had ambitions of recreating the Roman Empire, had the altar moved to the banks of the Tiber in 1938.