Puerta de Hierro

Puerta de Hierro is a monument of the second half of the 18th century, located in the northwest of Madrid, Spain, in the district of Moncloa near the Monte de El Pardo. It occupies a landscaped traffic island, defined by several branches of the highway A-6 and M-30, an enclave which is difficult to access. It is built in classical Baroque style.

Source: Wikipedia