Checking in at Elwood

I have a big bunch of keys for my third storey space. I call it a space because it remains empty, bereft of my possessions and therefore of me. Today I tested some keys. One for the front door, one for the back, another for the garage and another for the back gate. But what is the fifth one for?

I drove back across the West Gate Bridge with everyone else who was driving across the West Gate Bridge. Slow traffic. Pretty sky.