Pentillie Castle was built on the banks or the River Tamar in 1698 by James Tillie. It was adapted in 1809 into a castle and then reduced in size in 1968. It has been recently restored into a venue suitable for Weddings, corporate meetings and conferences, as well as relaxing holidays.
Here is the main path down from the Castle to the Boat House on the River Tamar. There are many such walks within the Estate.
See http://www.pentillie.co.uk/ for more details.