The name of the museum should really have 'Antonio Salinas' at the end but that made it too long.
Unlike in Agrigento and Siracusa, this is not purpose built. It was once a convent and came near to being bomb wreckage!
However it's as good an archaeological museum as you'd expect to find in Sicily's capital [GOOD]. It's especially worth going if you are heading to or from the wonderful Greek remains at Selinunte.
There is a certain ritual about whether the top floor is open - just ask and you'll be taken up. it's worth doing because the Orpheus mosaic is a beauty.