Tickets can be purchased directly at the sites. We did not have to wait long.
Lisbon has lots of hills and cobblestone streets. Because of this, we opted to leave the stroller at home and carry our son instead.
Try to visit the Castelo de São Jorge in the late afternoon when it’s less crowded and bigger groups have gone. The sunlight at this time of day is especially picturesque.
September or October is the perfect time to visit. It’s still nice and warm but not too hot for children.