Fortunately I've never had a bike stolen. When we moved to our current house it didn't have a garage (not that uncommon in the UK) and I had more bikes than I could easily store in a shed. So I built a big storage box in front of the house and installed a heavy duty ground anchor so that not only were the bikes out of sight but also securely locked to something solid. The box is built from floorboard grade pine so it wouldn't be that hard to break into, but so far nobody has tried.