Yes, you absolutely need a ticket to enter the Castelo de São Jorge in Lisbon, Portugal. It is one of the most popular monuments in the country, and access to the castle's interior, the archaeological site, and the "Camera Obscura" is strictly regulated via a paid entry system. As of 2026, adult tickets cost approximately 15€, though there are discounts for seniors, students, and families. For residents of the Lisbon municipality, entry is free, but tourists must pay. It is highly recommended to purchase your tickets online in advance, as the ticket office at the castle gate can have wait times exceeding 45 minutes during the peak summer and holiday seasons. Once inside, the ticket grants you access to the castle's legendary "miradouros" (viewpoints) which offer the best 360-degree views of the Tagus River and Lisbon's terracotta rooftops. The ticket also includes a small museum and the "Black Chamber," which provides a real-time view of the city using a periscope. Because the castle sits on the highest hill in the Alfama district, even the walk up to the entrance is an experience in itself, but the ticket is the only way to get behind the historic Moorish walls.