Join一 upcoming events being held in Orio al Serio. Orio al Serio is a charming city in the Lombardy region of Italy, best known as the home to Orio al Serio International Airport, one of the busiest airports in the country, and offering visitors a taste of classic Italian culture and history through its well-preserved medieval architecture, such as the Castle of Orio al Serio and the Church of San Martino, as well as local cuisine and nearby natural attractions like the Brembana Valley.