A section of wall dating back to the early 19th century overlooking one of Rome's most historic squares -- Piazza del Popolo -- crumbled on Wednesday due to the heatwave that is sweeping Italy.

Rome mayor Gianni Alemanno visited the area where nine metres (30 feet) of wall have been damaged on a winding road with panoramic views over the Eternal City that connects the square to the Villa Borghese park on top of the hill.

The road has been closed to traffic and Alemanno promised the damage would be repaired "in the coming days" and cost around 300,000 euros ($374,000).

"This is a direct consequences of the extreme climate," Umberto Broccoli, the administrator of Rome's cultural treasures, told reporters.

"First there was snow, then a very rainy winter and now a very dry summer."

The wall was built as part of a vast project by neoclassical Italian architect Giuseppe Valadier (1762-1839) to create a panoramic promenade in the centre of Rome and includes the famous Pincio terrace in Villa Borghese.