The official red and blue colours of Cagliari mirror those featured on the stemma of Cagliari. The red parts of the stemma are a reference to the coat of arms of the House of Savoy, a family which was previously the monarchy of Italy and more relevantly to Cagliari in particular, the Kingdom of Sardinia. The blue part of the stemma features the sky and the sea, also a castle; this is because the old historic centre of Cagliari is walled and called the Castello. Due to the use of these colours on their shirt in halves, the club is commonly nicknamed rossoblu.