Well, what Philip II did among the facts other answers may say about, was stopping the expansion to the west European area of the Ottoman empire, by defeating its fleet at the naval battle around the Gulf of Lepanto near the south of Italy, which at that time was under Spanish influence.
He set out Madrid as the Spain’s capital city,in the geographic middle of the peninsula, not only as a symbol of centralism, but as a mean to be reachable equalitarily from the coastal majority of Spain’s cities, so that northern, eastern, southern and western areas were not too distant to feel left aside`.
He also defeated the French army at St Quentin, and to commemorate this made Juan de Herrera design and build the Monasterio de El Escorial, near Madrid.
