Festive celebrations populate every page of the European calendar, but there is no question that summer reigns as a busy season for fun events in Europe. Whether you stumble into a European summer festival as the result of a serendipitous twist of fate or attend after years of planning, attending an event this time of year is the perfect way to put a cherry on top of any European trip. Festivals like the running of the bulls, La Tomatina (Spain's tomato-throwing festival) and Oktoberfest may garner the boldest headlines and biggest crowds, but a second tier of amusing and quirky festivals in Europe are also well worth seeking out. See: 5 Places to Get Your European Fairytale FixJuly 2 and August 16Move the Kentucky Derby to the piazza of a Tuscan hill town and put fierce neighborhood pride on the line instead of horse racing prestige and you have a taste of what Il Palio is all about. Siena, one of Tuscany's most charming cities, is home to this riveting horse race twice a year, and crowds come from near and far to be a part of this centuries-old thrill ride. The city is divided into 17 districts called contrade, and during the race each contrada is represented by a jockey. The jockeys race bareback around a dirt track in the Piazza del Campo for approximately 90 seconds. The race is so heated, it's not uncommon to see riders thrown from their horses. The winning contrada gets the spoils, a banner called a palio to put on a high pedestal in their neighborhood alongside district pride until the next ride. June 23 to June 24If you have always dreamed about what it would be like to wander the streets of a riverside town whacking strangers over the head with a plastic hammer — and let's face it, who hasn't? — Porto's Festa de São João (Festival of St. John) is the celebration for you. Saint John is Porto's patron saint, and every year the town uses his feast day as an excuse to let loose and have a two-day fiesta. The party percolates during family gatherings on the afternoon of June 23, gathers steam throughout a firework-filled evening and then boils over to beach parties welcoming sunrise on St. John's Day, June 24. Throughout all the fun, the historic hilly streets of Porto are alive with singing, dancing, wine-swigging and the ubiquitous bopping of soft, plastic hammers on heads. The toy hammer-to-the-head tradition originated as a light tap from a green vegetable, but has evolved over the years and taken on a life of its own. Make sure to rise from your St. John's Day slumber by the afternoon of June 24, so you can hustle to the Douro River to witness a regatta featuring vintage wooden boats, which traditionally transported the city's gift to the world: port wine. See: 5 Epic Day Trips to Take in EuropeLast Monday in MayIt may paint a funny visual, but the Cooper's Hill Cheese-Rolling and Wake in Gloucestershire is no laughing matter to those who participate in the chase. At the top of a steep hill in the emerald green English countryside, a wheel of Double Gloucester cheese is let loose, reaching breakneck speeds as it whizzes down the incline being chased by scores of citizens looking to survive the descent and claim the prize. The reward is just a wheel of cheese, but the bragging rights at the pub last a lifetime. Spectators are the real winners at the raucous event, as they are regularly treated to hilarious scenes of racers going head over heels down the hill on their quest to be a cheese champion. June 29With its penchant for food fight-like celebrations, Spain may very well be the capital of "projectile festivals," most notably Los Indianos, where revelers toss talcum powder on one another; Els Enfarinats, a flour-flinging fest; and La Tomatina, Spain's famous tomato-hurling celebration. So, it only seems natural that a wine-soaked fiesta would somehow spring to life in Spain as well, and the northern region of La Rioja provides just that. The Haro Wine Festival starts quietly with a long procession to a local church for mass, but on the way back, the rowdiness begins as the crowds start drenching each other with the local red wine via water guns, buckets and any other spraying device they can get their hands on. Participants whose white shirts have been turned pink then flock en masse to Haro's medieval town center to polish off the rest of the vino while swapping tips for removing wine stains. See: Europe's Best Island EscapesAbout the author: Born in the U.S.A. like Springsteen, but trying to see the world like Pitbull, Scott Hartbeck currently resides in Europe and is on a mission to uncover every corner of the Old Continent. His travel site, Worldwide Scott, is home to tales from Europe and beyond. For the short version, you can follow him on Twitter @worldwideScott.