Called the Flussbad (“river pool”), the goal of the project is the permanent transformation of a 1.5km stretch of river that has gone unused for more than 100 years into a new site for sitting, watching, relaxing and swimming.

The lower section of the course of the river, currently channelled as a canal, will be made into a space accessible to the public via two broad shoreline stairways at the Lustgarten and the Schlossplatz. The design alterations in this sensitive city-planning area, part of which belongs to the tourist-mobbed Museum Island, a UNESCO world cultural heritage site, are restricted to a minimum.

The former canal in the middle of these historical environs will house the proposed public swimming site.

These stairways provide access to a natural swimming pool 745m long, for the water flowing through this arm of the river has bathing water quality. A functional changing facility with lockers serving the practical needs of swimmers is invisibly integrated in the unused lower storey of the former Kaiser Monument.

The filtered water comes from the upper reaches of this section of the river, which lies about 1.2m higher than the pool. There, on a stretch 390m long, a 7.200m2 constructed wetland is inserted into the canal profile to purify the running water in a natural way. The 640-m uppermost section of the river that continues from there will be ‘renatured’. To this end, the northern shore wall will be completely removed and the course of the river gently widened into the grounds of the Fischerinsel. As an auxiliary purpose, this section serves as an inner city green area and preliminary water purifier. The actual main purpose of this side arm of the river is as a wildlife refuge, to support the resettling of riparian flora and fauna in the channelled main arm of the Spree River in Berlin’s urban area