On the rooftop of Casa Mila, the "Pedrera Soldiers" are ventilation shafts for chimneys. Casa Mila was the last building of architect Antoni Gaudi before he devoted himself entirely to the design and construction of la Sagrada Familia. The building of Casa Mila was completed in 1912. Gaudi was known for making very unique designs that also served very practical purposes. Casa Mila became a UNESCO World Heritage Site in 1984.