Quinta do Gradil, considered as one of the oldest estates, if not the oldest one, part of Cadaval Municipality, has a secular historical background and forms a significant architectural landmark. The documentary references found concerning Quinta do Gradil go back to the end of the 15th century, in a Royal document. On 14 February 1492, the date of the document, D. Martinho de Noronha received from King John II a letter of donation of the jurisdiction and rents from the Municipality of Cadaval and Quinta do Gradil. On the occasion of the ascension of King Manuel I to the Portuguese throne, and his actions in favour of the members of the House of Braganza, reference was made to Quinta do Gradil in the confirmation of the donation made by King Manuel I to Álvaro de Braganza, youngest brother of the 3rd Duke of Braganza, D. Fernando II, who was sentenced to be beheaded for treason by King John II in 1483. Quinta was acquired by the Marquis of Pombal, on the occasion of the movement that, from 1760, led to the occupation of municipal lands. It is established that it was already involved in the cultivation of vineyards at the time, a fact that must have been the decisive factor for the statesman responsible for the creation of the Companhia das Vinhas do Alto Douro, the Dourowine producing company. It continued as a possession of the family until the middle of the 20th century, when it was bought by Sampaio de Oliveira. Then, at the end of the 1990s, the current owner, Luís Vieira, acquired this estate. The historical buildings include a Pombaline palace, a chapel, a Mill, a granary, a stone aqueduct, a "mãe de água" or water house, a water tank and the imposing cellar.