Besides the “Amerika” park in Františkovy Lázně, Wiedermann Park is another great deed of the local Beautifying Society, and considering its area of over 44 ha, is the largest forest and park complex ever built by it. Until the end of the 19th century, the municipal parks to the east reached no further than the railway embankment constructed in 1865, which prevented any further developments in this direction for many decades to come. It was not until the planting and adjustment of the land that was to become “Amerika” to the south-east was completed that the society’s attention was directed to the east, where another forest dividing the town from the surrounding agricultural land was to be established. For this purpose, beginning in 1901, properties located in the area between the road leading to Chlum Svaté Máří (then known as Maria Kulm) and Tršnice (Tirschnitz) were gradually purchased, most of which was forested even before the onset of the First World War. Already in 1911, a wide gravel path that connected the new lots was also built.
In contrast to today’s preferred natural forest landscapes, the growth was then considered as a coniferous forest from the very outset. Just as Gustav Wiedermann mentioned in his call from 1878 to establish the society, the new planting of growths should provide a welcome change to the ever-present English parks. In 1911, on the occasion of the 30th anniversary of the society, Wiedermann could look back at a job well done with pleasure: “Over 660,000 new seedlings have been planted so far on the societal and municipal properties.” The work of the Františkovy Lázně Beautifying Society could not be overlooked. Therefore, to the west, a small “El Dorado”, the desired forest, spread out instead of swamplands, and to the east, a new park created by thousands of young firs and pines stood.
Three years later, on 11 February 1914, Gustav Wiedermann died, and as the long-term Chairman (from 1889-1914), he bequeathed the not inconsiderable amount of 5,000 crowns to the society. Therefore, at the society meeting held on 29 May 1914, the idea to rename the park after its creator, who also fell so in love with the place, was proposed by Josef Carl Fischer, and the decision was approved. In 1915, a stone building that was originally intended as a shelter for visitors in inclement weather was built in Wiedermann Park. However, at the suggestion of mayor Eugen Loimann, the building, aside from the lookout tower, was built also as the quarters for the park administrator. This new “cottage” costing 6,400 crowns was ceremoniously opened on 16 April 1916. Known under the name of “Tower of Gratitude” (“Dankwarte”, today the Château), the construction was to be a permanent monument of the society’s gratitude to the deceased, as well as to all benefactors of the society, whose names were immortalised on the marble plaque placed in the commemorative hall built on the ground floor.
The park continued to flourish under Franz Köppl, Wiedermann’s successor as the society’s chairman, under whose chairmanship (1914–1935) Wiedermann Park became an even more popular excursion destination than "Amerika”. Already during the First World War, the park was connected to all other societal property thanks to the new path. Benches with signs giving the elevation above sea level were installed in the park, fruit trees were planted, and in 1926, when pheasants were introduced to the park, suitable plants for their sustenance were also planted. Aside from organising hunts, the Františkovy Lázně Sports Club began organising annual trap shooting events on the so-called Sun Meadow beginning in the 1920s. The appearance of the forest park was changed by World War II and the ensuing cultural-historical turn of events when most of the town residents were forcefully expelled. In the second half of the twentieth century, the town was divided in two not far from the "Château” by the ring road, and without the conscientious work of the society, it continued to fall into disrepair.