Bocadillo de Calamares is a classic Madrid street food that is a must-try when visiting the Royal Palace. It consists of a crusty baguette filled with deep-fried squid rings. The squid is typically seasoned with salt and served with a squeeze of lemon juice. The combination of the crispy squid and the soft bread creates a delicious and satisfying sandwich. Bocadillo de Calamares can be found in many food stalls and bars around Madrid, especially in the popular Plaza Mayor area.