The authority believes that the landmark is an important symbol for the town of Åtvidaberg and its history.
The solar cannon tower is built in red brick and stands on Kanonkullen next to Bysjön.
The point of a solar cannon is to use the sun itself to fire the cannon.
If it is cloudless, the sun's rays shine in through a narrow window in the tower at 13:00 during the summer.
The sunlight is captured by a burning glass that ignites the gunpowder and the cannon is fired.
If it is cloudy, stubin is used instead.
- The solar cannon tower has an extremely high cultural-historical value as it is considered to be the only preserved with a functioning and operational solar cannon in all of Sweden.
It feels very good to protect the building for future generations, says Patrick Björklund, county antiquarian and unit manager for the unit for cultural environment at the County Administrative Board of Östergötland in a press release.
Built in 1853
The solar cannon tower was built by Baron Seth Adelswräd, son of Jan Carl Adelswärd, in 1853 after he had seen a solar cannon tower during his travels in France.
160 years later, the Association of Åtvidaberg's Tourist Entrepreneurs and Åtvidaberg's Guid Group raised the question of declaring the Solkanon Tower a building.
The protection means that it may not be demolished or moved or rebuilt, rebuilt or otherwise altered either externally or internally.
There are divided opinions about when the cannon was fired in the past.
Some believe that it signaled when it was time to eat, while others believe that it fired when it was time for a party at the nearby Adelsnäs manor.
See Lars Rasch from Solkanonklubben fire the cannon.