The Wieliczka graduation tower is built of larch wood. This wood was specially chosen as larch is extremely durable. Larch wood stored in dry conditions can last even 1800 year, while in water approximately 500 years. This is the only kind of wood that will not rot in sea water.
The larch construction is covered with bundles of blackthorn branches. Blackthorn or otherwise called sloe, is a thorn plant which grows in almost every part of Europe. It forms a dense thicket and supplies hardwood. It is necessary to cut the branches at a specific time while thinking of constructing a graduation tower – when the leaves drop off and the sap flows back to its roots.
For over a year several dozens of workers were employed at the construction of the tower. The graduation tower dimensions are as follows:
- 7,348 m² - development area
- 1,843 m² – build-up area
- 9 m – construction height
- 22.5 m – height of the octagonal tower from which one can admire a magnificent view of the mine surroundings
- 7,600 m³ – cubage
- 275 m³ – brine reservoir volume
- ca. 500 m³ – of used larch wood cl. C24
- 766 m³ – reinforced concrete construction cubage
- 3,200 m² – surface area of the blackthorn elevation
- 100 – the number of tourist and patients that can visit the graduation tower and be in the yard at the same time; the walls of the graduation tower and viewing platform will also be accessible.
There are only three graduation towers in Poland larger than the one in Wieliczka, but all of them are located north of Warsaw. This means that within the radius of 300 kilometers of Wieliczka there is no such facility of such a dimension. The largest graduation towers are located in Ciechocinek, Konstancin-Jeziorna, Inowrocław and Gołdap. There are several mini-towers (operating on a similar working principle) that also function in Grudziądz, Busko-Zdrój, Rabka Zdrój, Sołonka and Dębowiec. Graduation towers operating in neighbouring with Poland Germany - (20 facilities), also in Austria (1 graduation tower).