We decided to climb all the stairs in the tower, hoping we would enjoy the view. It paid off, climbing the stairs was very exciting for my children (we pretended we were knights:)), we had lots of fun with "traffic lights" - there are traffic light on the stairs, making the traffic one way in order to avoid jams (the staircase is very narrow). The surrounding area is nice as well. There is a little bar near by (where I had the most expensive coffee in Lisbon - but still cheap compared to my home country). Overall I recommend the visit, provided that you have time for it.
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