Erice's Spanish Quarter is an unfinished military complex on the edge of the hill town, built to house Spanish garrisons but never completed as intended. Its stonework and exposed position make it one of the more atmospheric stops outside the main lanes.
The site is worth including on a circuit of Erice's walls, churches, and viewpoints. It is less polished than the central monuments, but the coastal views and historical backstory make the detour worthwhile.