The city plays host to the Live at Heart festival, one of Sweden's largest musical showcase events.

[citation needed] In the 12th century the first foundations of a castle were established, with the construction of a round tower for guard and lookout.

Kalmar's strategic location, near the Danish border (at the time the Scanian lands, i.e. the provinces of Blekinge, Halland and Scania, were part of Denmark), and its harbour and trade, also involved it in several feuds.

After the Treaty of Roskilde in 1658, the strategic importance of Kalmar gradually diminished as the borders of Sweden were redrawn further south.

The cathedral was designed by Nicodemus Tessin the Elder and is one of the foremost examples of baroque classicism in Sweden.

Its design reflects the complex interaction between the new style, liturgical considerations, tradition and the fortress-city requirements.

A local trucking firm, which employs nearly 450 people, has installed computers that track fuel efficiency and have cut diesel use by 10 percent, paying off the cost of the devices in just a year.

[4] A large wood pulp plant harnesses the steam and hot water it once released as waste to provide heating, through below-ground pipes, and generates enough electricity to power its own operations and 20,000 homes.

[4] Bicycle lanes are common; for example, the Kalmarsundsleden,[5] and cars line up at Kalmar city's public biogas pump.

Street lights use low-energy sodium bulbs, and car dealers promote fuel-efficient and hybrid vehicles.

The stadium was also built to host concerts and did so in the summer of 2011 when Swedish artists Håkan Hellström and The Ark performed.