Predeal Monastery is a small Orthodox complex founded in 1774, located on the quieter southern edge of the town, set back from the main road in a forested clearing. It is modest in scale — a stone church dedicated to the Nativity of the Virgin Mary, a smaller older chapel dedicated to Saint Nicholas, and a handful of monastic buildings — but the setting is peaceful and the frescoes inside the main church are worth a look.
Unlike the grander monasteries of Sinaia or Curtea de Argeș, this one attracts few tourists and remains a working community. You are likely to have it largely to yourself.