There are plenty of interesting historic sights around Copenhagen for a day trip, like the outstanding Renaissance style Kronborg Castle. Please note it's also easy to visit in Malmö, Sweden over the Øresund Bridge which is the longest combined road and rail bridge in Europe.
At the heart of Malmö lies the Big Square (Stortorget). There is a statue of King Karl X Gustav of Sweden, who took the city from Danish dominion. The ornate Malmö City Hall (built in 1546) is on the east side, and in the northwest corner is Kockska Huset, the house of Jörgen Kock, a German immigrant who became mayor of the city and achieved wealth simply and directly: by taking control of the city mint. In the winter the square becomes a skating rink.
Carlsberg center is located in Valby at the location of the first Carlsberg Brewery. The visitor centre will give you an idea of how the world-famous Carlsberg Beer is made. Carlsberg is among the largest tourist attractions in Copenhagen. The Old Carlsberg Brewery from 1847 has been converted into a modern centre for visitors which exhibits the history of the beer.
Château de Niort is a medieval castle in the French town of Niort. It consists of two square towers, linked by a 15th-century building and dominates the Sèvre Niortaise valley.
The two donjons are the only remaining part of the castle. The castle was started by Henry II Plantagenet in the 12th century and completed by Richard the Lionheart. It was defended by a rectangular curtain wall and was damaged during the Wars of Religion. In the 18th century, the castle served as a prison.
The present keeps were the central point of a massive fortress. The southern keep is 28m tall, reinforced with turrets. The northern tower is slightly shorter at 23m. Both are flanked with circular turrets at the corners as well as semicircular buttresses. Each of the towers has a spiral staircase serving the upper floors. The Romanesque architecture is of a high quality with the dressed stones closely jointed.