We visited on a sunny afternoon. There as a lovely view over Pompey Harbour.
The museum has lots of interesting stuff for all ages: like mock-ups of a military hospital, officers' and squaddies' mess, etc.; and then loads of cannons from old horse drawn ones through to piece of Saddam Hussain's cannon (aka for a petrochemical plant - likely story).
Can't say I'm a fan on militetia, but worth a visit. We did run out of steam as there are so many cannons.
Our daughter liked the tunnels round the site.
There is a column nearby dedicated to Nelson.
Nice cafe too (but not barista coffee).
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