I really like monitors a lot, i think its the ginat out of proportion turret on what is essentially a small ship.
Several parts on the tour had to do with firing and aiming the guns, and with all the complications the main guns could still fire at a rate of 8 shells per minute.
A&B turrets from the deck
At the end of the visit I had the impression of a powerful and technically complicated ship (the engine room was a massive tangle of pipes and gauges which would have been increadily cramped and hot to work in). I only we had had the foresight to save one of our battleships for the nation, not just this cruiser.
It cost me £13.50 for enterance and I spent a good couple of hours looking round. The price also includes free use of an audio guide. I enjoyed it and was well worth it I reckon.