Scastles is a map I (Tom 7) spent a lot of time on for the now-defunct (but excellent) Q3F mod for Quake 3! It's based vaguely on an old map for Threewave CTF (Quake 1) called Da Ancient Wargrounds. Long live the old school!
Some older screenshots:
Here's a shot of the front of the blue base:
The atrium by the respawn rooms:
The front of the base holds the capture point:
Besides the front entrance, you can enter by climbing the rocks, or
entering the broken right silo:
Or enter on either side from the water:
Here's the ramp room:
Which connects directly to the flag room...