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.
The Château de Foix dominates the town of Foix. An important tourist site, it is known as a centre of the Cathars. Built on an older 7th-century fortification, the castle is known from 987. In 1002, it was mentioned in the will of Roger I, Count of Carcassonne, who bequeathed the fortress to his youngest child, Bernard. In effect, the family ruling over the region were installed here which allowed them to control access to the upper Ariège valley and to keep surveillance from this strategic point over the lower land, protected behind impregnable walls.
In 1034, the castle became capital of the County of Foix and played a decisive role in medieval military history. During the two following centuries, the castle was home to Counts with shining personalities who became the soul of the Occitan resistance during the crusade against the Albigensians.