Everyone was so happy we showed up in Pisa they decided to throw us a firework display on our last night there. ... kidding. We were lucky enough to show up on a major holy holiday in Pisa on the 17th, Saint Raineri’s Luminara. It was a light festival along with an regatta race down the river called The San Ranieri Regatta, a feast called, "Saint Rainerius’s Feast" (you see the theme) and fireworks at night. It was a blast! Beautiful watching the fireworks go off from the bridge over the river. It was unique because the same fireworks display about 10 different places along the river. Some of the videos and pictures george this. The buildings along the Arno River also had candle displays on the side. You can make it out in the videos (the buildings just seem a little too bright).
Saint Raineri is the patron saint of Pisa. His name can be spelled multiple ways, apparently.
You can read more about him here: