If you turn from the ancient Via Flavia at Ponte Porton, you will find yourself on a road climbing up the hill, where the old burial/sepulchral church of St. Stephen built in the 14th or 15th century, with a part of a wooden altar belonging to the ancient church of St. Anthony, still stands. In the middle of the cemetery there is a big cross with a bronze sculpture of Christ. From the Kostanjica crossroad a road leads to Biloslav, a village where the Parenzana railroad station used to be.

Past the cemetery, the road winds down to the ancient village of Kostanjica. The place was inhabited in ancient times; graves and inscriptions from the Roman era have been found. The parish church has been dedicated to the Virgin Mary, Peter and Paul. It bears the Electamus Genoa 1769 inscription. It was rebuilt in 1500 and expanded in the year mentioned in the inscription. There are three altars, the biggest one, made of marble, displays statues of St. Paul and St. Peter. In front of the church there is a sandstone bell tower built during the Venetian rule; it has square ground-plan and octagonal belfry. On the arch one can read year 1766. The village is almost completely deserted; only a few people live by the main road. Houses have interesting architectural features, typical of Istrian villages: long balconies, small terraces and outdoor hearths for cooking and barbecuing.

Old cobblestone streets

In the late 14th century, during the Austrian rule, surrounding villages were populated by Wallachians. Venice took over in 1510, and the Worms Edict of 1521 confirmed the status. In 1530 Venice auctioned Kostanjica and it became, along with Zavrsje and Bercenigla, property of Giustignano Contarini, a citizen of Venice. The Contarini family owned it until the 18th century. There was also a Castagna family, whose coat of arms is still visible on an old façade. After the plague of 1630 Venice encouraged immigration of Croats from Dalmatia and other regions.

Local population has always been agricultural; fertile soil provided all the necessary aliments. Inhabitants of Kostanjica also worked on boats which transported timber down the river, from Bastija to the Mirna Harbour (Porto Quieto). They were called battellanti (bargemen).