A number of stones with grooves exist on Gotland. Archaeologists interpret these grooves as traces of an unknown industrial process in the High Middle Ages.There are approximately 3700 grinding grooves, of which about 750 occur in the solid limestone outcrop and the rest in other rock formations. The latter often consist of hard rocks such as granite or gneiss, but also soft rocks such as sandstone occur. Grinding grooves are also found in Sk�ne, in southern Sweden and in Finland. Astronomer G�ran Henriksson dates a number of these grinding grooves to the Stone Age, between about 3300 BCE to about 2000 BCE, based on astronomical alignments, although his methodology has been heavily criticized.
The medieval town of Visby has been entered as a site of the UNESCO World heritage programme. An impressive feature of Visby is the fortress wall that surrounds the old city, dating from the 13th century.
The inhabitants of Gotland traditionally spoke their own language, known as Gutnish. Today however, they have adapted a dialect of Swedish that is known as "Gotl�ndska". In the 13th century, a work containing the laws of the island, called "The Gotlandic law" (Gutalagen), was published in the ancient Gutnish language.
Gotland is famous for its 94 medieval churches, most of which are restored and in active use. These churches exhibit two major styles of architecture: Romanesque and Gothic. The older churches were constructed in the Romanesque style from 1150�1250 AD. The newer churches were constructed in the Gothic architectural style that prevailed from about 1250-1400 AD. The oldest painting inside one of the churches on Gotland stretches as far back in time as the 12th century.
The valknut symbol has its most discovered examples on Gotland.
Traditional games of skill like Kubb, P�rk, and Varpa are played on Gotland. They are part of what has become called "Gutniska Lekar", and are performed preferably on the Midsummer�s Eve
