Legend has it that Roskilde was founded by this chap called King Ro and that he built a little town around a spring he liked very much. Well, he subsequently named the town after himself and the spring as "kilde" means "spring" in Danish.
In reality of course, this story is little more than hogwash. Roskilde was founded by another chap with a more hip-sounding name, King Harald Bluetooth, in the 990's. Then again, Bluetooth Town sounds more like a place in Silicon Valley right? I'd rather take in the legend anytime...
Bpacker's Roskilde page
Try out how it is to be a viking and jump in as the locals do into the harbour - winter or summer! (and of course when this photo was taken it was rather cold!!) - along with being naked - is fine!