As early as the 14th century, there were water mills on the site of today’s Nové mlýny (New Mills) Street where a road leading from the Gothic Church of St Clement turns towards the Vltava River. The mills were called New, as recorded in 1484. In addition to the New Mills, there were Lodní (Ship), Helmovské, and Lodecké Mills nearby. Most of them were razed in the early 20th century, depriving Prague of outstanding Renaissance architecture of a technical nature.
The water tower, which used to supply the lower New Town, is the only reminder of the original mills. The tower must have been erected after 1602 because in that year the provincial millers demanded that the New Town Council build new waterworks at New Mills. The water tower was equipped with a covered lookout platform with twelve windows; the space between them was decorated with portraits of Bohemian princes and kings from Přemysl the Ploughman to Holy Roman Emperor Rudolf II. A similar depiction of Czech statehood appeared in an earlier sacral building, the Romanesque rotunda of St Catherine in Znojmo, featuring an unknown artist’s paintings of the Přemyslid rulers on the walls.
The 1655 flood severely damaged the tower which had to be built again, probably using some parts of the previous one. The present six-floor tower with a generous lookout area comes from 1658–1660. Under the lookout area floor was a water tank (water was pumped from the Vltava because the tower was formerly located on the riverbank) and water ran by gravity through piping into fountains in the wider vicinity. The inner space of the tower, which is encircled by a staircase, was not separated horizontally as it is today; it was a narrow space which contained a system of pushing and gravity-based water pipelines. The area was heated to prevent the water from freezing. Fragments of a furnace which was uncovered during the latest research are visible near the ticket office on the ground floor. At the end of the 19th century, the water supply function of the tower was discontinued. Modern waterworks with remote irrigation delivery conduits began to supply Prague with water.
The New Mill Water Tower included an unparalleled lookout area, known as ‘Lusthaus’, at the time of its construction during the 17th century. It was a space for pastime meetings of town representatives; one may also see it as the first lookout tower in Prague, though a non-public one that was intended for town nobility only. Large windows provided a good view of the wide vicinity and inner walls were equipped with prime-quality smooth plaster and a decorative cornice featuring a relief. Assumingly, a wooden barrel (false) vault formed the roof; however, it appears not to have survived the Prussian bombing of 1757. Apart from two parapet bays, the plaster comes from the period after the severe fire of the tower in 1689. In two parapet bays (on the south and north) fragments of plaster have survived from the time of the tower construction. The decoration of the lookout floor introduces a late mannerist area which along with the entrance tower portal bestows an extraordinary look onto the otherwise purpose-built technical structure.