The castle sits on a hill overlooking Lisbon; I could see it from everywhere I went. But, when I tried to find it to visit it, I got hopelessly lost. Do not trust the signs that are posted around and just ask someone how to get there! When you enter the castle walls, there's a small community of homes and shops inside. I'm not sure how I would feel having tourists tromping through my backyard all day every day, so I left that area alone. The cost to enter is about $10 (or about 7 euro). The line was long but moved quickly and the folks selling tickets and souvenirs appear to speak every major European language as well as English. The castle isn't much to look at. You can walk along the walls (be careful -- an older woman came crashing down the stairs while I was there and was banged up pretty bad) and look out over the city, but that's about it. There was a man playing guitar in the central square area. If you wander away from the crowds, you'll find the archeological ruins dig area, where they are excavating some Moorish and Iron Age communities. I enjoyed the shaded castle grounds the most. It was a hot day and it was nice to enjoy a cold soda under a shade tree. Know that it's a good uphill climb to get to the castle entrance; if your feet can't take the cobblestones in Alfama, this climb won't feel too good and you may want to take a cab. There's a cafe there if you're hungry or need a drink. Not much for the kids to look at but it is a good view over the city.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.