Brooksby Village in Peabody is the headline example on the North Shore. It is an Erickson Senior Living continuing care community on 90 acres for residents 62 and better, with a fitness center, an indoor heated pool and hot tub, six restaurants, and hundreds of resident-run clubs and activities. Residents often describe it as a small town under one roof, and one visit makes it easy to see why.
Kaplan Estates, on Lynnfield Street in Peabody, is also a continuing care community, and it is rated by US News. It deserves a tour alongside Brooksby so you can compare two very different feels in the same town.
Farther out, 55+ active adult communities extend the options. Del Webb offers 55+ communities in North Reading, just north of Boston, for owners who want the resort lifestyle without the continuing care piece. Pulte's Riverside Woods in Andover is a 62+ community with elevator buildings, secured access, and wooded trails that lead down to the Merrimack River.
Treat all of these as examples to explore rather than a ranking. Every community has its own personality, its own fee structure, and its own way of doing things, and the right one is the one that fits how you actually want to live. The honest next step is to visit a few and compare them in person.