The 18th Century library in the converted church where 'X marks the spot' is actually still a church. It's the Church of San Barnaba. The interior of the chuch is open to the public
Where Sean Connery scares the seagulls off the beack and they crash the attacking plane. This is the Monsul Beach, in San Jose (Cabo de Gata, Almeria)
Is a mine zone, with a lot of tunnels and is very dangerous.
Location of the final scenes when leaving the Valley of the Cresent Moon