For the rest of the 16th and through the 17th Century, pizza grew to be a very popular dish -- first with the local peasants and as time went on, with travelers who had heard of this exotic dish. Travelers would visit the poorer neighborhoods to taste the wares of the men known as "pizzaioli."
Generally regarded as the first Italian pizza restaurant is Antica Pizzeria Port'Alba in Naples (of course). They baked pizzas for vendors as early as 1738, but became a pizzeria in 1830 and are still in operation today.
It wasn't just the poor and the tourists who loved pizza. By the middle of the eighteenth century, pizza in Italy had achieved royal status. Maria Carolina d'Asburgo Lorena, Queen of Naples and wife of King Ferdinando IV, was such a big fan that she had a special oven built at Capodimonte so their chef could prepare and serve pizza.