Once a decade, the stars of Documenta, Skulptur Projekte Münster and the Venice Biennale align to form a constellation of events making up a modern-day grand tour of art festivals in Western Europe. When this special occasion occurs, nearly every gallery with participating artists at these events heads to Basel in June, to visit either Art Basel or the regular satellite fairs of Liste and Volta—and to show off the names featured in these key showcases, wisely capitalizing on collectors’ interest before the art-world stars realign and the sky changes, come September.

• Switzerland