It is presumed that around 1750 a chapel was built near the spring to, in modern terms, formalize this pilgrimage.
However, some fragmentary writings relate that during the year 1660, a collection was organized in Thann to rebuild 'a miraculous chapel of Our Lady of Brunnon or Bramai near Bréchaumont, which had been destroyed by fire shortly before'. Etymologically, Brunnon could be related to Brunnen, meaning well or fountain in German.

We cannot obviously affirm that it was the chapel of Bellefontaine, but in any case, there must have existed at the time, in the vicinity, a sanctuary or oratory which, around 1750, was replaced by a new building.

Another document dated 1751 and entitled "Memorandum of what is owed to the parish priest of Traubach-Bréchaumont and Gebenatte for the processions" stipulates the following:
"1751 ... plus in the same year a procession in the chapel of the Belle Fontaine and applied mass = 4 pounds" and after 1752, still according to the same source, there were 2 then 3 processions at this place.

The archives of the State of Bern also reveal that on February 28, 1755, the parish priest of Traubach, on which Bréchaumont then depended, Jacques-Xavier Hürt, informed the Bishop of Basel of the granting, by the Pope, to the Chapel of Bellefontaine, of a plenary indulgence for a period of 10 years and of which he requested the renewal by the same letter.

This fact demonstrates the importance of the pilgrimage at that time , which continued to grow until the Revolution.