The Birkenstock Madrid is the oldest member of the family of models, making it a classic. Launched as a “fitness sandal” half a century ago, this simple single-strap model has gone on to become a firm fashion favourite. Its function and design have largely remained unchanged. The special positioning of the strap gently trains the muscles in the feet and calves with each step – the toes’ grip reflexes trigger this effect. Madrid Big Buckle Black Nubuck Leather