As Boris has explained below, the Botanical Garden of the University of Basel invited us for a mini sketch crawl (prologued by a very nice dinner) during the Museum's Night last Friday. We sketched with students of the scientific visualization courses of the University of Zurich. Due to the heavy rain there wasn't as many visitors as in previous years, but I'm sure that those who defied the weather enjoyed the many botanical wonders and the lively atmosphere in the greenhouses. I had a great time too and only stopped sketching when our host, Heinz Schneider, switched off the lights at around two.
Some more sketches here.