The patron of Casciago is Saint Eusebius, celebrated on 1 August in the Church of Sant'Eusebio.
Already in the second half of the 16th century, the church square is mentioned as the cemetery of the then-small community, and in the time of Saint Charles Borromeo the cult of Saint Eusebius grew more prominent, with many devotees gathering on 1 August. In the early 20th century the religious feast also became a fair of the Varese area, with profane aspects that still persist today: the eve, on 31 July, opens with the burning of the balloon, a globe of flammable material hung in the square. The town also holds the Campo dei Fiori regional park.
