The largest Bohemian pond which is named after the owners of the domain - the Rožmberks - was built by the important Czech pond designer and regent of the domain Jakub Krčín between 1584 - 1590, on the Lužnice river about 6 km north of the town Třeboň.
Jakub Krčín also designed a project of the water canal called Nová Řeka (New River) for draining of redundant water from the Lužnice into the Nežárka river and protect the pond from floods.
The huge dam, planted with four lines of oak trees, has 55 m thick foundations and on the top it is 13.5 m thick. It is 11.5 high and its length is 2.4 km. The area of the pond is 489 ha.
The instructional trail Rožmberk leads around the pond and the path of the trail Okolo Třeboně passes the pond.