Lisbon Tram 15E

Tram 15E is the practical Belem line. It links the central riverfront with the western sights: Jeronimos Monastery, Belem, the coach museum side, and the Alges direction.

This is the line I would think of as transport first. It is less romantic than 28E, but more useful if the day is Belem rather than hill-city texture.

The tram can still get crowded because every visitor eventually points west. If it is jammed, compare it against the train from Cais do Sodre toward Belem/Algés or a rideshare. Lisbon gives you options, so do not turn a simple Belem day into a tram purity test.