Cleaver, who has run the business for 40 years, has put Kilchurn Castle and the freeholds for four hotels in Dalmally, Oban and Tyndrum, up for sale.
Kilchurn Castle, situated on Loch Awe, is managed by Historic Scotland. It was built in the 15th century but was destroyed by a storm in the 17th century and abandoned shortly after. The remains of a fallen turret remain in the courtyard.
The hotels included in the business are the 96-room Royal Hotel, the 132-room Ben Doran Hotel, both in Tyndrum, along with the 99-room Dalmally Hotel and Oban’s 66-room Alexandra Hotel. The sale also includes a fleet of 16 coaches
Cleaver bought the Royal Hotel in the 1970s and expanded his empire over the years before announcing his retirement and selling the firm in 2015. The business now makes an annual turnover of £8m.
Alistair Letham, a director at the selling agency Colliers International, said: "Mr Cleaver is a somewhat legendary business figure in Argyll, who built the company up from scratch, so the buyer will be following in illustrious footsteps.”