Yes, for a visit in 2026, it is highly recommended to book tickets online in advance for Castelo de São Jorge in Lisbon. While you can buy tickets at the gate, the queues can often exceed 60 to 90 minutes during the peak travel months (May to September). By booking through the official portal (EGEAC), you receive a digital ticket with a QR code that allows you to use the "Fast Track" or "Pre-paid" entry line, saving significant time. In 2026, the castle also utilizes a capacity management system, meaning that during extremely busy periods, walk-up tickets may be timed for several hours later or sold out entirely for the day. Advance booking also ensures you can secure a spot for the Camera Obscura (Periscope) tour, which is a popular attraction inside the castle with very limited daily sessions. Tickets for adults are generally around €15, with discounts available for youth, seniors, and Lisbon residents who have their documented proof ready at the gate.