Kärnan - Tower on the top of the hill. 100 SEK to go up the tower. Description from the Internet (https://helsingborg.se/uppleva-och-gora/kultur-och-museer/the-keep-of-helsingborg/):

Kärnan – the keep of Helsingborg The building of Kärnan started in the 1310s and was finalised around 1320. Today, the tower is 35 m high and each side of the tower is 15 m wide. The octagonal structure on the front façade is the stair turret, and the projecting structure on the northern wall covers the drain for the privies. Around the tower are the ruins of a collar wall that was built to protect Kärnan from bombardments. Immediately south of the entrance stairs, are the foundations of an inner barbican turret leading to the drawbridge. The circular paved marking in the gravel at the foot of the entrance stairs outline the foundations of the oldest known predecessor of the current tower, a keep built in the 1100s. This round tower was either reinforced or replaced sometime before Kärnan was built. The remains of these new construction works are outlined by the square structure. Kärnan functioned as a central keep in a large castle, and was facilitated with lodgings for the royal family. Within the castle area – the bailey, elaborated hall buildings were crowded together with kitchen and storage facilities, stables and garrisons. A 500 m long ring wall, with several turrets and gatehouses, encircled the bailey. The chapel of St Michael, to the north of the Terrace Stairs, was built into the wall and thereby also became a part of the castle defence. Archaeological excavations have uncovered traces of the everyday life at the castle as well as remains of the more firmly built structures that once existed. A medieval cemetery has also been detected by St Michael’s chapel. The oldest remains suggest that the area was taken into use by the late 1000s or early 1100s. New excavations will be an important way to find out more about the castle and its history. Scania was a part of Denmark until the treaty of Roskilde in 1658. The castle of Helsingborg, with its strategic location in the narrowest part of the Öresund, was one of the strongest and most important fortifications for the Danish crown. It was heavily damaged during the Danish-Swedish wars in the 1600s. The Swedish king Karl XI gave the order to demolish the castle in the 1680s. Kärnan was to be blown up, but the king failed to give the final permission. With only the keep left, the castle lost its importance. The name Kärnan, Swedish for core, is known from the 1700s, before that it was known as the tower of Helsingborg. The tower as it stands today is very much a result of a renovation in 1893-94. Beside extensive refurbishments, Kärnan was re-designed in a neo-gothic view of the Middle Ages. The most characteristic part is the viewing platform on the added top floor with its battlement. The stairs leading up to the keep was built in 1903.