Crownhill Fort, Plymouth

This is a Victorian Fort built to defend Plymouth from attack. Obsolete for its original purpose, it was later used as a barracks. There is quite a lot to see, with gun emplacements, embankments, tunnels etc. The Fort is owned by the Landmark Trust. Unfortunately it is not open daily to the public, but there are pre-booked tours and events during the year. If you are interested, you should look on the website and book a tour or event. I found it a most interesting place to explore.
My sister just reminded me about this access nightmare – approaching from the north a right turn is required, and it took some time to escape a tangle of looping service roads and get on the other side of the dual carriageway.
(Looking at the digital mapping today, it appears that turning off onto the B3413 Crownhill Road may not work, and you have to continue south to the big A386/A38 roundabout and execute a U-turn. Another possibility is to take an early right turn at the Looseleigh Lane roundabout and then approach circuitously along the B3373.)