The Round House
Probably the best bit about a visit to The Kymin is the drive up from Monmouth; a twisty steep road with enough hairpin bends to make it feel like its in the Alps.
When you get to the top, apart from the stunning views, what is there to see?
There is the odd little Round House, the even odder Naval Temple (situated on top of a hill over 15 miles - 25km - from the sea), and Beaulieu Wood, a fine area of ancient woodland.
The Round House completed in 1796 was built as a Georgian Banqueting House by a group of local gentlemen who enjoyed picnicking in the area. The National Trust opens it on certain days (see their web site), but the day I was there was not one of them.
The Naval Temple was built in 1801 to commemorate sixteen admirals who had delivered significant victories at sea, including Nelson’s destruction of the French fleet at the Battle of the Nile in 1798. Nelson and Lady Hamilton visited the site in 1802. Since then it has been restored many times, the last being in 2012.
With a bit more research there is probably a decent walk to be had from here.