The Monastery of Alcobaça is a UNESCO World Heritage site located in Alcobaça, Portugal. Founded in 1153 by the Cistercian order, it is one of the earliest Gothic structures in the country. The monastery is renowned for its impressive architecture, including a stunning church and a beautiful cloister. Inside, visitors can find the tombs of Pedro I of Portugal and Inês de Castro, a famous tragic love story in Portuguese history. The monastery also houses a rich collection of religious art and artifacts, making it an important cultural and historical landmark in Portugal.