Photo from the early excavations in Tingstäde träsk.
Lake Tingstäde, originally referred to as a swamp in Sweden, is one of the last lakes remaining on Gotland. In the 1800s, piles standing upright were discovered in the lake. But it would take until the early 1900s before the site began to be investigated. During early surveys, it emerged that locals called the site “boulwarki”, which roughly translates to “bulwark”. The modern-day word “bulwark” is used to refer to a defense installation, so today the remains are called “Bulverket” or “Bålverket” in Swedish.
The Bulwark was an enormous wooden structure built out on the lake. It was square, with each side 170 metres long and about 30 metres wide and consisting of cisterns. There was an empty space in the middle of the bulwark. Many different buildings were part of this structure – homes as well as buildings for other activities. The wood is exceptionally preserved, so it would in theory be possible to piece the entire structure back together. You can even see traces of tools that were used. Around the entire structure was a palisade as an additional defence.
Wood samples have been dated to reveal that the trees used to build the bulwark were felled in the 1120s. All in all, around 25 000 trees, mainly pine, were felled for the construction. Despite the vast number of resources that went into felling, transport and construction, the society somehow continued to function. This likely indicates that someone, or several people, had enormous power in the area for such a project to be implemented. But even though different reasons abound for why it was built, we still do not know the origin story of the Bulwark.
Researchers will document the site using modern technology, and a 3D model of the remains will be produced. Since 2021, divers have been at work below the surface so we can better understand the buildings at the Bulwark. Read more on the website of C.H.A.B. Archaeology & Building Conservation.