The cellar of Macul was commissioned by Luis Cousiño to a firm of French architects in 1870. Located in the centre of the property, it was built using bricks and limestone stuck together with lime and ridge; a mixture of sand and egg white. The basement was built seven metres deep with double walls where an air flow circulates to create a passive ventilation system. This guarantees a constant temperature of 14ºC and a humidity close to 75% for the optimum maturation of the wine in barrels. This wonder of the 19th century is considered one of the most efficient and grandiose cellars in the world.