May 1 is a national holiday so you're likely to find many shops and services closed and big crowds in major tourist destinations like Venice or Alberobello (both places I recently made the mistake of visiting on May 1), but you're also likely to find parades, festivals, and concerts. If you're on the island of Sardinia, don't miss the Sagra di Sant Efisio, one of the island's most important events. A colorful 4-day procession with decorated oxcarts and horsemen accompanying the saint's statue leads from Cagliari to the Romanesque church of Saint Efisio on the beach at Nora where there will be food and dancing.

