Tram 28 is the cheapest and most popular way to visit the city. For 3 euros, we cross the city in 1 hour 30 (we can make it both ways). The most difficult is to find a seat. A few days in Lisbon has reminded me of a time when cities lived more in harmony with their environment. On can still see traces of a more sustainable lifestyle with  tiles acting as air conditioning, electric trams, small neighborhoods like microcosms, where one lives as in a village, marble sidewalks that have not moved for centuries. Thank you Lisbon!