June in Portugal is generally known as the month to celebrate different saints. Festa de São João is actually the culmination of the five-week festivities. Traditional music, dances, jumping over bonfires and eating grilled sardines—that's how the city of Porto celebrates Festa de São João that takes place every year during Midsummer, on June 23. Thousands of people go out to pay tribute to St. John and enjoy magnificent fireworks at midnight.
This festival includes some interesting pagan traditions. For example, people on the streets might hit each other with garlic flowers or inflatable hammers. The fireworks are also deemed to have profane roots paying tribute to the Sun as the deity. In fact, it began in the 14th century as a pagan tradition of worshipping the Sun and crops. So similar festivities that we observe nowadays have taken place in Porto for over six centuries, but the figure of Saint John the Baptist became so important to the citizens only in the 19th century. Since then the celebration obtained Christian meaning and was established as the city's most prominent holiday.
Another curiosity—it's not widely known beyond Portugal, even though it's in fact, one of the liveliest street celebrations that take place in the country.