At the age of 26, Cosimo of Medici the Third set out on a long trip through Europe between 1668 and 1669. The places he visited, which were important for cultural, economic or political reasons, were carefully selected in order to prepare the Prince for becoming the new Grand Duke of Florence. His visit to Spain involved one of the longest journeys, including a stay in Madrid where he enjoyed some of the pleasures of the Spanish Court, such as comedies, music, chocolate, perfumes and local delicacies. He also visited the royal palaces and their rich collections to satisfy his cultural interests. This article deals with the Prince's visit to the Palace of Aranjuez, and identifies and analyses the buildings, fountains, hydraulic machines and paintings he saw, in order to reconstruct the condition of the Royal Palace at the time of the visit.