Castillo Mallorca, located on its own private peninsula has been put up for sale by German-based real estate agents Engel and Voelkers.
The 1,400-square metre (15,000-square feet) property is about 20 minutes from Majorca's capital Palma de Mallorca and comes with a swimming pool and a private jetty for yachts of up to 30 metres in length.
The main house — there is also a guest house — contains a 'Lady Diana' suite which is where the princess stayed.
Despite Castillo Mallorca's heavy price tag the agents handing the property are pretty confident about a sale.
"This is a unique property in a unique location and we think the current German owner will get something very close to the asking price," a spokesperson for Engel and Voelkers told The Local.
There had already been interest from Chinese, Swiss and Spanish buyers, he added.