Bond, Targovi And Orlaith

James Bond makes a night-time sea crossing to reach Doctor No's island and, in a later political period, climbs a high wall with pitons to enter Blofeld's Castle of Death. (And see here.)

Targovi scales a high wall to enter what he discovers to be a secret Merseian base on Zacharia Island on the planet, Daedalus.

In SM Stirling's The Sky-Blue Wolves, the main Korean fort, protected by mountain-high walls with no openings, is entered by easily defended tunnels from many well-guarded subsidiary forts. Since physical attack on the main fort is impossible, Orlaith plans a psychic assault. Read on.