Look out for pickpockets - one trick is to hop on the metro, stand in the doorway (look confused) whilst 2-3 conspirators close in behind and go through you stuff as you try to get by before the doors close (when they make a fast exit and you're minus your valuables). Similarly crowded trams can be a problem and notices warn the unwary.

metro tram buses

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Watch out for pickpockets - I know EVERYONE says this, but I used to live in Lisbon and I saw it happen time and time again on the 28 and 15 trams. - Especially by the ticket machines on the new 15s

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