A woods of olive trees planted between the 14th and 17th centuries, trees with majestic, twisting, gnarly trunks protected by a lush green canopy of leaves. S’Ortu mannu means ‘great orchard’ and is a nature oasis covering some 13 hectares (originally it measured 500 hectares). It lies at the feet of mount Exi, at the top of which are the remains of the Gioiosa Guardia castle, built between the 12th and 13th centuries at the behest of the Della Gherardesca counts, and lies circa 3 km from the town of Villamassargia. The park, so designated in 2001, is home to 700 centuries-old monumental olive trees that were planted in the Middle Ages, when Benedictine monks first put the roots of the first grove into the ground. Legend has it that the Pisans encouraged the locals to graft more trees, which they, the locals, would then own. Whether this is true or not, the grove counts many trees which, until recently, were the property of individual citizens. When the town took over s’Ortu mannu, each of these trees was entrusted to the family of the original owner. Almost every family in Villamassargia tends to a tree in this oasis, proof of the strong ties the population has with its land, important ties handed down through the generations.