Naples is traditionally credited as the home of pizza. This originated as a meal for the poor, but under Ferdinand IV it became popular among the upper classes: famously, the Margherita pizza was named after Queen Margherita of Savoy after her visit to the city. Cooked traditionally in a wood-burning oven, the ingredients of Neapolitan pizza have been strictly regulated by law since 2004 and must include wheat flour type "00" with the addition of flour type "0" yeast, natural mineral water, peeled tomatoes or fresh cherry tomatoes, mozzarella, sea salt, and extra virgin olive oil.

Source: Wikipedia