Look at the socket of the statue of William de Zwijger also known as Prince of Orange. (1533–1584), a Dutch statesman, who was the initial leader of the Dutch Revolt against the Spanish and founding father of the Dutch Republic.
The Spanish placed a price on his head and on 10 July 1584, he was shot here in the Prinsenhof in Delft (the building next to you). The bullet holes are still in the wall there. He was buried in the New Church on the Markt. He is the founder of the Orange-Nassau family and an ancestor of the current King of the Netherlands. More about his history here.