Boston collects the way other cities build skylines. An encyclopedic art museum with nearly half a million works, a palazzo frozen in time, a science museum standing on a dam across the Charles, a four-story ocean tank downtown, and contemporary art cantilevered over the harbor — all of it a T ride apart.

The MFA and the Gardner

The Museum of Fine Arts holds nearly half a million works — ancient Egyptian galleries, Japanese art, one of the great Impressionist collections anywhere, whole wings of American painting. You could visit weekly for a year and keep finding new rooms. A short walk away, the Isabella Stewart Gardner Museum is its opposite: a Venetian-style palazzo built around a flowering courtyard, every object still hung exactly where Isabella arranged it a century ago. The empty frames still hang where the paintings belong — thirteen works vanished in a 1990 heist that remains unsolved, and the museum has left the spaces waiting ever since.

Science, sea turtles, and the harbor

The Museum of Science straddles the Charles on its own dam, its hands-on halls having quietly converted generations of kids into engineers. Downtown, the New England Aquarium wraps a spiral ramp around its four-story Giant Ocean Tank, a Caribbean reef where sea turtles and rays circle past at eye level. And in the Seaport, the Institute of Contemporary Art cantilevers out over the water, the harbor framed in its windows becoming part of every show.

Playing it smart

Group visits by geography: the MFA and the Gardner make a natural day, the ICA anchors a Seaport evening, and the Aquarium sits steps from the harbor ferries. Many museums run free or discounted admission windows — certain evenings, library passes, neighborhood days — but the details shift, so check our full museums guide before you plan. And when the weather turns, this is the best rainy-day material in the city — we’ve sketched a few ready-made plans in our itineraries.