April 25 is a national holiday celebrating liberation day in Italy. Some services may be closed but there will be festivals and concerts in many places.
Easter, Pasqua, often falls in April. Italian Easter celebrations start during the week before Easter and continue through Easter Monday, La Pasquetta, a national holiday and a day where you may find some very interesting festivals.
Easter in Italy
Palio della Rana, frog race, usually takes place the weekend after Easter in the town of Fermignano, between Urbino and Urbania in central Italy's Marche region. Contestants, representing each of the seven contrade or neighborhoods, dress in historic costume and race with frogs atop small wheelbarrows, trying to reach the finish line before the frog hops off. There's also a procession in historical costume and food.
Il Giuramento di Pontida: In early April, there is a historical re-enactment of the alliance between the Lombard cities of Bergamo, Brescia, Mantova, and Cremona against Federico Barbarossa on April 7, 1167. The town of Pontida is 16km from Bergamo.
Rome's birthday: The date of Rome's founding (in 753BC) is celebrated on April 21 so if you're in Rome, watch for festivals, concerts, and special events. There's usually a fireworks display over the Tiber River and gladiator shows around the forum area. Find out more in April Events in Rome.
Saint George's Day: In Caresana in the Piedmont region, Saint George's Day on April 23 is celebrated with the Palio dei Buoi, a parade of floats pulled by oxen. Saint George is the patron saint of farm workers.
Festival of San Marco: Saint Mark, San Marco, is the patron saint of Venice and there is a festival in Saint Mark's Square on April 25 including a procession to the basilica. On this day in Venice you should give a rose to your loved one. Find out more in April Events in Venice.
The Race of the Ring: The Corsa all'anello in Narni in the Umbria region is part of the celebrations held the last week of April. During this medieval jousting competition, three horsemen try to snare rings. There are also a historical procession and other events.
San Biagio Day is April 28. San Biagio, the patron saint of Avetrana in southern Puglia, is celebrated with a 2-day festival including bands, food, street fair, and a religious procession. Avetrana and San Biagio Festival Pictures
Free Museums and Archeological Sites
In mid to late April the Italian Ministry of Cultural Heritage and Activities usually sponsors Settimana della Cultura, Week of Culture. National museums and archeological sites have free admission and some have special events and guided tours. Sites not normally open to the public are sometimes opened during this week, too. Check the web site (in Italian) for dates and events. Note: Probably cancelled in 2013
Florence's museums are open at night with free admission and there are concerts and special events all around the city on April 30 for the Notte Bianca, or white night.