Birkenstock Madrid Sandals. The Birkenstock Madrid is the oldest member of the family of models, making it a veritable classic. Launched as a “gymnastics sandal" half a century ago, this simple single-strap model has gone on to become a firm fashion favorite. The upper is made from the skin-friendly, hard-wearing synthetic material Birko-Flor® in a sophisticated nubuck look which boasts a texture and color that could almost be mistaken for real leather. Anatomically shaped cork-latex footbed. Birko-Flor® nubuck upper. Suede footbed lining. EVA sole. One strap with an individually adjustable metal pin buckle. Imported.