Your own private island with a castle and hidden coves up for grabs as incredible £2.7 million Spanish property hits the market

Published: 08:54 EST, 10 November 2026 | Updated: 08:54 EST, 10 November 2026 Forget splashing millions on a sprawling mansion or luxury villa – for £2.7million you could have an entire private island complete with your very own castle. Set in the middle of the El Burguillo reservoir, Isla Centinela spans an impressive 10,000 square metres and offers a secluded escape surrounded by water.Just an hour from Madrid, the Spanish island is home to a remarkable castle dating back to 1923, which has been transformed from a former watchtower into an extraordinary four-storey residence.Boasting imposing towers and floor-to-ceiling windows, the property offers spectacular views across the Ávila mountains and the surrounding reservoir.Inside, exposed brick walls, original-looking timber features and rich dark wood finishes give the castle plenty of character, blending historic charm with the comforts of a modern home. Private island Isla Centinela has hit the market for €3.25million (£2.7million) The 10,000 square metres of land with a castle has been listed by Century 21 Homeplace The castle boasts four floors and was previously a watch tower before being transformed into the impressive abode it is todayThe lucky buyer will have the choice of seven suites – perfect for hosting – and each one has a fireplace.Elsewhere in the castle, there is a professional bar and entertainment space that has the capacity to be changed into four more bedrooms.Other areas include a living room, kitchen, garage and storeroom. The impressive piece of land is listed for sale by Century 21 Homeplace for €3.25million (£2.7million), with Ignacio La Iglesia acting as the real estate advisor.It's a self-sustainable spot, with a water purification and filtration system as well as solar panels and a back-up generator. The island itself has private coves and woodland to explore without worrying about bumping into tourists like on the mainland.There is also a jetty perfect for accessing the island when water levels are high.Water levels drop enough during part of the year that the island connects to the mainland and can be accessed by car. The property is surrounded by amazing views of the Avila mountains and surrounding reservoir The new owner will have the choice of seven suitesBut Isla Centinela isn't the only private island on the market at the moment, Stroggilo Island in the Dodecanese, the group of islands in the southeastern Aegean Sea which includes Rhodes and Kos, is up for sale – offering potential buyers 'a blank canvas'.The 54-acre isle, which once sheltered sailors seeking refuge from bad weather, promises year-round greenery, a stunning coastline, incredible views and raw natural beauty.While there are plenty of neighbouring smaller islands nearby, including Patmos and Leros, the nearest popular tourist island is Kos, around 45 nautical miles away. 'As one of the most accessible undeveloped islands in the region, it offers a "blank canvas" for a visionary owner,' the listing explains. The island has hit the market for €4.5million (£3.8million) on listing site Private Islands Inc.