Pena Palace (Grounds Only)
Bus 434 from Sintra station to the top. Grounds-only ticket gets you 80% of the experience — all terraces, ramparts, and the exterior photo spots. We were skeptical about fitting this in with only 90 minutes, but it's totally doable if you speed-walk the highlights: Triton gate, the front terrace, the western viewpoint. You're on a schedule today.
Arrive before 09:30. We once tried catching the 10:15 bus and the queue wrapped around the station — cost us nearly an hour.