In the purgatory of winter, this is little more than a sordid shack next to a curious lake called “Galgenweel.” But once the grips of winter give way to balmy summer days and long evenings, “BAR LEFT” awakens on the left bank of the Scheldt. Lounge chairs are laid out and drinks are served by the blue-washed staircase at this great pop-up bar. Tourists are rare here, but are very much welcome. “It’s mine, but it’s yours,” boast the owners.