As we head into the summer, we scouted the globe—from London to Dallas to Miami to New York—to select what we feel are the must-see museum exhibitions this season. Sure, the beach is great (I’ll be along the Mediterranean coast in Forte dei Marmi, Italy, in a few weeks), but summer is also, as with any season, an essential time for taking in some art (or, in the case of one of our selections, dozens of incredibly rare stones). In Dallas, we recommend stopping by the Nasher Sculpture Center to view Thaddeus Mosley’s alchemical wood sculptures, arranged like a jazz quintet grooving on a stage. At the Tate Britain in London, I recently saw Isaac Julian’s astounding, profound “What Freedom Is to Me” retrospective and can’t recommend it enough. In New York, I just visited the American Museum of Natural History, home to a new Jeanne Gang–designed addition, where a small-but-potent, green-themed exhibition of jewelry from the collection of Van Cleef & Arpels is on view. Next, I plan to head to Sarah Sze’s whirlwind of a show at the Guggenheim. Also on the docket (for the fall, if not the summer, or maybe during Art Basel Miami Beach in December): “Joan Didion: What She Means” at the Pérez Art Museum Miami.