For a first-time visitor in 2026, 3 to 4 days is the "sweet spot" for Lisbon. A supportive peer "itinerary" guide: two days allows you to cover the historic core (Alfama, Baixa, and Chiado) and the Belém district. A third day is essential for a day trip to the fairytale town of Sintra, which is just a 40-minute train ride away. If you have a fourth day, you can explore the LX Factory, the Tile Museum, or take a short trip to the beaches of Cascais. Lisbon is very hilly and "slow-paced," so rushing through it in 48 hours often leads to exhaustion. By spending four days, you have time to enjoy the Fado music in the evenings and long lunches without feeling like you’re just checking boxes. If you want to include the Algarve or Porto, you’ll need a much longer stay in Portugal.