Few people would remember it now but the narrow Härjapea River used to flow through the city of Tallinn. During the Middle Ages it was one of the most exploited rivers in Estonia. Eight watermills were built along the river and as industries grew, the river became increasingly polluted.
Härjapea jõgi
By the 19th century the Härjapea River was partially covered with planks to deal with the pollution issue. Then in 1930 the river was sealed completely. Today, only underground sewer pipes remain.
