Because these three islands are so different from each other, it's worth visiting them all. Isola Bella, the nearest, is occupied mainly by Palazzo Borromeo, whose formally terraced gardens are open from April through October. The largest island, Isola Madre, has perhaps the most spectacular gardens of the whole area. It is a subtropical paradise (open April-October). Isola dei Pescatori, the third island, is a charming fishermen's village.
Lake Orta is a tiny jewel compared to Lake Maggiore, but it is utterly enchanting. The hills and mountains are closer here, and somehow this lends a fairy-tale atmosphere to the villages surrounding the water. The nicest is Orta San Giulio, whose pretty little town hall has a frescoed façade and whose narrow streets are lined with rococo homes. From here, take a ferry (or row your own rowboat) to the even more picturesque San Giulio Island. Pop into the 12th-century romanesque church to see its pulpit, one of the outstanding works of medieval sculpture in northern Italy.
Back in town, stroll up the hill from Piazza Motta until you reach the Sacro Monte, a flower-filled hillside dotted with 20 chapels dedicated to St. Francis.