We usually try to join a walking tour the day after we land. This gives us a brief history of the city and an idea of surrounding neighbourhoods to visit.
We joined Sandemans New Europe walking tour for Lisbon. It’s a free tour and just have to pay gratuity to the guide. We also did the same for Paris. The guides are very engaging as they depend on your tips at the end. We also got to see the oldest bookstore in the world. The Betrand. The city is over 3000 years old, so many layers of history nestled in every streets.