Elvaston Castle - it's a folly, inspired (I think) by one of the Harrington family's 19th century trips to the Middle East. They're restoring it at the moment, and even without glass in it's oval stone windows (behind the scaffolding), it looks beautiful - can't wait to get inside and see the eastern-influenced decoration.
The thing is, I've been to Elvaston Castle more than a few times, and I've never seen it before - shows you there's always something new to learn. After that free lesson from the world around me, I took another look at Elvaston Castle itself with new eyes, and got another brilliant idea for my YA novel, Coalface- remind me to tell you about that after the rewrites.
So if you're looking for inspiration, get away from your normal environment, and see what's out there - let me know what you find.