The construction of the castle began in 1508 the starost of Kazimierz, Mikołaj Firlej. It was continued by his son, the voivode of Ruthenia, Piotr Firlej. At the end of the sixteenth century, the castle passed into the hands of Tarłowie and thanks to their efforts has been considerably expanded. It obtained the final shape in the second half of XVII century, in the period when it belonged to the Lubomirski family, who rebuilt it after the damage inflicted by the Swedes. Unfortunately, in 1783 Jerzy Marcin Lubomirski lost the castle in cards, and subsequent owners were unable to maintain it. From the beginning of the nineteenth century, an uninhabited residence began to fall into ruin.
The extended plan of the castle has been adapted to the topography of the hill. The buildings located in the eastern part come from the original site: the gatehouse and bastion, the residential tower, the so-called avant-corps in the south elevation, fragments of the eastern and western walls. However, the earliest defense device should be considered a tower erected in south-east corner of the castle, which was rebuilt in the first half of XVII century to the palace tower. This palace, built between 1577-1585 by Santi Gucci, filled a southern curtain. It was two-storey, with a sequence of five rooms on the representative second floor. From the side of the courtyard there was a cloister, with stairs leading to the first floor. At the turn of the 16th and 17th centuries a cylindrical tower was erected in the south-east corner and at the beginning of the seventeenth century, the second, western courtyard.
The castle is in a state of a ruin, although work is slowly being carried out to restore some of its former appearance. The cloisters were reconstructed in the eastern part of the courtyard, the northern palace and the western apartment combined with a cylindrical tower, which was also restored. Currently, there is a small hotel and museum with an exhibition about the history of Janowiec and its former owners.
Leksykon zamków w Polsce, L.Kajzer, S.Kołodziejski, J.Salm, Warszawa 2003.