7 Museums
Interesting article for those who plan to stay in Lime one or few days.
IMHO, my selection from these 7 would be:
The National Archaeological Museum
Lima Art Museum
The Museum of Santo Domingo Convent and Catacombs
The Museum of Gold
Additional personal tips:
The Larco Herrera museum: An unforgivable omission in this list (mentioned in the comments).
The National Museum, Museo de la Nación. I visited 2 years ago and it was a bit unattended, many exhibitions were closed or removed to the Archaeological museum. If it remains the same, I would by pass it.