Located seven and a half miles inland from the coastal town of Poreč, Višnjan has, in my opinion, relatively little of interest to offer … unless, that is, you happen to be interested in taking a course in astronomy, in which case you will have come to the right place: Višnjan is home to the largest astronomical observatory in Croatia, and it runs numerous international courses over the summer, not only in astronomy but also in biology and archaeology.
The influx of international students at this time of year therefore creates a lively, laid-back atmosphere in the town, and its numerous bars and restaurants get particularly busy. For the normal visitor, however, Višnjan is just a simple little town with not much of interest to offer, despite its pretty historic centre. You will probably find it preferable instead to head for the Istrian coast or some of the more picturesque neighbouring towns such as Buje.