Once a year, Porto does something wonderfully strange. The entire city floods into the streets, the sky fills with glowing paper balloons drifting upwards, and strangers cheerfully tap each other on the head with squeaky plastic hammers. This is São João, Porto's most beloved festival, and one of the most unique nights in all of Europe. To truly experience it, the secret is simple: start the day slowly, and save your energy for a night that doesn't end. 10:00 AM: Discover Por