Kalmar Castle is a historic landmark located in Kalmar, Sweden. It was built in the 12th century as a defensive fortress and was later expanded and modified in the 16th century to become a royal residence. The castle played a significant role in Swedish history, serving as a stronghold during the Kalmar Union in the 14th century and being the site of the signing of the Kalmar Union treaty in 1397.

The castle is well-preserved and features a unique combination of Gothic and Renaissance architecture. The castle's interior includes several grand halls, chapels, and banquet rooms, as well as a museum showcasing the history of the castle and its role in Swedish history. The castle also boasts a stunning collection of tapestries, many of which were woven in Brussels in the 16th and 17th centuries. Visitors can also explore the castle's tower, which provides panoramic views of the city and surrounding landscape.

Today, Kalmar Castle is a popular tourist attraction and is open to the public year-round. It is also a popular venue for events, such as weddings and concerts, and hosts various cultural events throughout the year.