Former Victorian premier Jeff Kennett has savaged developer Caydon's $1 billion high-rise proposal for the historic Nylex silos alongside Melbourne's Yarra River calling it "an overdeveloped, underdesigned monster".

Mr Kennett, who works from an office nearby, is leading a Melbourne establishment backlash to Caydon's plans to build a series of high-rise towers on the 1.4 hectare former Richmond Maltings site in Cremorne, famous for its concrete silos and Nylex Plastics sign.