Sidra, or cider, is a traditional Spanish drink that is enjoyed in Madrid and other regions of Spain. It is made from fermented apple juice and has a slightly tart and fizzy taste. Sidra is often poured from a height to create bubbles and enhance its flavor. It is typically served in small glasses and is a popular choice for pairing with traditional Spanish dishes, such as tortilla española or pulpo a la gallega. Sidra is a refreshing and unique drink to try while in Madrid.