WEST SPRINGFIELD — In a glitzy ceremony replete with a rock concert and glass cases full of music memorabilia, Hard Rock International today unveiled a proposal for a casino complex that could cost $700 million to $800 million at the Eastern States Exposition fairgrounds in West Springfield, home of The Big E agricultural fair.

Forty acres of the 175-acre fairgrounds would be dedicated to the new resort, said Jim Allen, chairman of Hard Rock. The project will include shops and restaurants, a hotel, a rooftop pool, a spa, a concert venue, and 25,000 square feet of convention space, Allen said.