Lisbon is a wonderful city, with an immense natural beauty and an intense living atmosphere. If you can take the opportunity to spend some days visiting Lisbon, here are some areas/monuments that you should not miss (personal point of view):

Lisbon can be quite warm in end of May, so please bring light clothing and, if some extra time is available, don't forget your bathing suit. Beautiful beaches are within 30 minutes of a very beautiful train ride (towards Estoril). For more information on Lisbon touristic places and/or agenda, please follow the Lisbon Tourist site (and we have more dozens of suggestions for +days/old comers,...)