Kernavė was a medieval capital of the Grand Duchy of Lithuania and today is a tourist attraction and an archeological site. In 2004 Kernavė Archaeological Site was included into UNESCO world heritage list. The area of Kernavė was sparingly inhabited at the end of the Paleolithic era, with the number of settlements significantly increasing in the Mesolithic and Neolithic eras. It is believed, that first inhabitants settled in Kernavė territory in 9-8 millennium BC, but only in the first centuries AD they started to form bigger settlements in the Pajauta valley (Kernavė territory). Settlements were protected by five fortified mounds, which still remain.
The town was first mentioned in 1279, when, as the capital of the Grand Duke Traidenis, it was besieged by the Teutonic Knights. In 1390, during the Lithuanian Civil War (1389–1392), the knights burned the town and its buildings in the Pajauta valley, including the castle. After this raid, the town wasn't rebuilt, and the remaining residents moved to the top of the hill instead of staying in the valley.
In later years, the remains of city were covered with an alluvial earth layer, that formed wet peat. It preserved most of the relics intact, and it is a treasure trove for archaeologists, leading some to call Kernavė the 'Troy of Lithuania'. For example, Kernavė has the oldest known medgrinda, a secret underwater road paved with wood. The road was used for defense and dates from the 4–7th centuries.
The site became the subject of wider interest again in the middle of 19th century, when a romantic writer, Feliks Bernatowicz, depicted the area in his novel Pojata, córka Lizdejki in 1826. The hillforts were soon excavated by the Tyszkiewicz brothers and then by Władysław Syrokomla (1859). After World War II, the excavation works were restarted by Vilnius University in 1979, and then again by the Lithuanian Institute of History between 1980–1983.
References:Celje Castle was once the largest fortification on Slovenian territory. The first fortified building on the site (a Romanesque palace) was built in the first half of the 13th century by the Counts of Heunburg from Carinthia on the stony outcrop on the western side of the ridge where the castle stands. It had five sides, or four plus the southern side, which was a natural defence. The first written records of the castle date back to between 1125 and 1137; it was probably built by Count Gunter. In the western section of the castle, there was a building with several floors. Remains of the walls of this palatium have survived. In the eastern section, there was an enclosed courtyard with large water reservoirs. The eastern wall, which protects the castle from its most exposed side, was around three metres thicker than the rest of the curtain wall. The wall was topped with a parapet and protected walkway.