The Peabody Essex Museum is one the highest rated museums in Massachusetts. It brings art, architecture, and culture together through it's many collections and rotating exhibits. No joke, you could easily spend the entire day here.
The Witch House is a must see if you want to get a glimpse into the daily life of a family living in Salem during the Witch Trials. Taken straight from their website, "Through examination of family life, architecture, and furniture of the seventeenth century, visitors will gain a deeper understanding of the people involved in the Witch Trials". It is advised that you purchase tickets for the Witch House in advance.