AXA are known as one of the top manufacturers of frame locks for bicycles, and their newest model, Victory, is their most secure version yet. The Victory has a hardened shackle, improved cylinder housing and more powerful plug-in locking system than it's predecessors, and a newly developed process allows for it to be welded all around, for even greater security.
Frame locks are a great option for locking up your bike, as it is attached to the frame of your bike, and therefore always there. Adding one of AXA's great plugin chains or cables gives you the ability to lock it to a fixed object, and secure the wheel with a single key.