On Sunday 24 July 2022, MONDORF Domaine Thermal held an Open Day to mark the 175th anniversary of hydrotherapy in Mondorf-les-Bains; linked with this public event, over 400 guests had received invitations for a celebratory lunch.

According to the MONDORF Domaine Thermal website (referring to the 1840s), "Under Dutch rule, the country and the region had to deal with a large number of taxes, including an exorbitant tax on salt. This tax was so high that Luxembourg farmers were unable to salt their meat, which led to a situation of scarcity and famine. To bypass the Batavian monopoly and tackle this major problem efficiently, the Société pour la Recherche des Ressources Naturelles [Society for the Research of Natural Resources] was set up and tasked with prospecting the Luxembourg subsoil in search of rock salt. After initial unsuccessful drilling, a survey was undertaken at the suggestion of the notary of Mondorf at the time, Maître J.P. Ledure, at the foot of the Mondorf Galgenbierg, from which a trickle of reddish, saline water would ooze out. Reaching a depth of more than 700 metres, this did not hit the expected rock salt, but it did manage to strike a significant, warm, and highly mineralized spring in 1841. It gave Maître Ledure the idea of a spa resort. A Société des Bains de Mondorf was soon established. The first people to take the waters arrived in Mondorf as early as 1847, under the auspices of Doctor Nicolas Schmit." For full background information, see

Before the lunch, Luxembourg's Prime Minister and two Deputy Prime Ministers had been invited, along with the Mayor of Mondorf-les-Bains, to address the invited guests on this auspicious day. A couple of changes were enforced, however, with the speeches being moved from the ampitheatre to an area close to the Luxembourg Aviation Museum and the Ciné Waasserhaus (cinema) which provided much more shade rather than the speakers being in the direct glare of the sun on a day when afternoon temperatures were in the mid-30s. The other change to the planned arrangements was that the country's Prime Minister, Xaviel Bettel, was unable to participate following his contracting COVID-19 (for the second time) within the past week.

The Mayor of Mondorf-les-Bains, Steve Reckel, spoke first and was followed by Deputy Prime Minister and Minister for Mobility and Public Works and Minister for Defence, Francois Bausch, and Deputy Prime Minister and Minister for Consumer Protection, Minister of Health and Minister Delegate of Social Security, Paulette Lenert.

A short walk followed across the stream that runs through the extensive gardens of MONDORF Domaine Thermal, over the footbridge (crossing into France) and past the Orangerie, where crémant was served to guests who by that time had become very thirsty.

Lunch was served at the Mondorf Plage under the Sahara tent, comprising an extensive salad buffet, followed by a BBQ buffet of fish, meat and vegetables, and a dessert buffet, including ice creams and sorbets. The hosts had laid on a sumptuous meal and the staff on duty during the event were conspicuous by their presence, ensuring that glasses never went empty and there was plenty of food to go around. Getting into the spirit of sustainability, staff encouraged guests to take home with them the various 175th anniversary branded (bakelite) glasses (crémant, wine, soft drinks, coffee) that they had used during the event, offering paper bags into which guests could put them.

Meanwhile, the Open Day was happening, with guided tours, and an exhibition on "hydrotherapy (thermalism) yesterday, today, tomorrow", as well as various other entertainment happening both indoors and outdoors, where there was also a BBQ and bar (also with many staff on duty).