I was riding the bus around downtown Stockholm to get home after a pretty late evening and I was too tired to read. I fired up my laptop and started to detect networks. I found six or seven... during 30 minutes. A week later a friend from Canada visited us. He stayed at a hotel in central Stockholm. He had a working network in some spots in his room. Apparently it belonged to a law firm.
Of course, unlike the golden age of hacking, the 1980s and earlier, such curious explorations are probably illegal these days, so Don't Do It, Kiddies.