Kalmar Cathedral is the defining building of the Baroque town plan that was laid out when the city was relocated from its medieval position near the castle to the present site in the 17th century. It was designed by Nicodemus Tessin the Elder and completed in 1682, making it one of the finest Baroque churches in Sweden — a category that doesn't get as much attention as it deserves.
The interior is spacious and well-proportioned, with a wide nave, painted vaults, and the kind of confident decorative programme that marks Tessin's best work. The cathedral occupies one end of the Stortorget (Grand Square), and together they represent a rare complete example of 17th-century Swedish urban planning: square, church, and surrounding buildings conceived as a single composition.
Entry is free and the cathedral is normally open during daytime hours. It is worth spending 20–30 minutes inside rather than simply looking at the exterior — the stonework and painted ceiling are the best part.