Getting from Lisbon Airport to the City: What I Learned the Expensive Way
I arrived at Lisbon Airport at 11pm on a Tuesday with two bags and approximately zero knowledge of how the city worked. I took a taxi. It cost €22 to Mouraria. This was fine, and it was also avoidable, and within a week I had learned to never take a taxi from the airport again.
The Metro is the answer. The Aeroporto station is on the Red Line (Linha Vermelha) and connects directly to the city centre in about 25 minutes. The ticket with the airport surcharge costs €1.79 plus a €0.50 card deposit for the Viva Viagem card. The full journey to Baixa-Chiado costs under €2.50 total. Buy the card at the airport machines before you leave the arrivals hall.
The Metro runs until about 1am. If you arrive later, the Aerobus (aerobus.pt) runs through the night and connects the airport to Cais do Sodré and other central points for €4. It takes longer and is less frequent but it exists.
Taxis and Uber both operate from the airport legally. The official taxi rank is outside arrivals and the metered fare to central Lisbon will be around €15-25 depending on traffic and destination. Uber is usually cheaper and has the advantage of showing you the price before you confirm. Neither is necessary if you have one bag and are going somewhere on the Metro network.
The one exception: if you are arriving with large luggage, arriving very late at night, or staying somewhere in Belém or Cascais that is not well-served by Metro, the taxi or Uber is worth it. Otherwise: Red Line, Viva Viagem, twenty-five minutes, done.
