We visited Porec in June 2006, it was the last stop during our trip through Croatia. The Basilica in its present form was built in the 6th Century, but the remains of older buildings show that the site was used long before for sacred purposes. In the centre of the complex is a beautiful atrium (photo, with the main portal of the basilica). I also climbed the bell tower, I always like to have a look at a town or site from above. But the highlights are the remains of Byzantine art in the basilica and the adjacent museum. The mosaics are reminiscent of other early Christian sites in the Adriatic region, such as Ravenna and Aquileia. Particularly the mosaics in the apse show great similarity to those in Ravenna, that you ask yourself whether they might have been made by the same artist.
We have only visited the basilica complex, at the end of our trip we were tired of crowded Croatian towns. But later trips in early spring have convinced me that Istria is a worthwhile destination: beautiful towns along the coast (eg Rovinj) and forested hills in the inland, where you can enjoy nature and simple but delicious traditional food.