While you can purchase tickets at the entrance gates of the Pompeii Archaeological Park, it is highly recommended to pre-purchase them online, especially in 2026. To manage extreme overcrowding and protect the fragile ruins, the park authorities have implemented a daily cap of 20,000 visitors. During the peak season (May to September), tickets often sell out several days in advance, and those without a reservation may be turned away at the gate. Furthermore, buying online allows you to skip the notoriously long "ticket window" lines, which can exceed an hour in the hot Italian sun. When you book online through the official "TicketOne" portal, you choose a specific entry time slot. If you are looking for a more "quiet" experience, it is best to book the earliest morning slot (9:00 AM) or a late afternoon slot. Also, keep in mind that the first Sunday of every month features free entry, but these days are incredibly crowded and do not allow for pre-booking, so you must arrive very early to stand in a manual queue.