Welcome to Copenhagen, Miner! While we'd love to show each and every one of you around, we don't encourage people to visit unannounced - we tend to be busy working after all, and unannounced guests take up time, cause distraction, and sets an unfortunate precedent - if we take *you* in, what about the next guest?
But if you do happen to be in the neighborhood and can't help yourself, I'd suggest knocking on late friday afternoons - we usually try to end a little early and kick back for a beer or two after work.