An excursion to 'mount a tour of recent construction'...

“Mounted on a tour of recent construction we admire the beautiful panorama that unfolds before our  eyes.”

Here is a quote from the famous excursion of SESA (Société d’Etudes Scientifique de l’Aude) reported by TISSEYRE - to Rennes-le-Chateau in 1905 (p99);

"Montés sur une tour de construction récente. nous allons admirer le beau panorama qui se déroule sous nos yeux. A notre gauche, la grande plaine de la Lauzet avec, au fond, le village de Granès et, plus à droite, Saint-Ferriol. Plus près, devant nous, sur un mamelon, s'élevait, parait-il. une forteresse qui défendait Rennes-le-Château aussi appelle-t-on ce mamelon « le Casteillas ». Rien pourtant ne subsiste et il est impossible au chercheur de trouver trace de constructions."

"Mounted on a tour of recent construction we admire the beautiful panorama that unfolds before our  eyes. To our left, the great plain of the Lauzet with, basically, the village of Granès and rightmost Saint-Ferriol. Closer to us, on a hill, was, it seems a fortresse. A fortress that defended Rennes-le-Château: also called "the Casteillas." But nothing remains and  it is impossible for the researcher to find traces of buildings".

How be it that those on the above excursion were able to 'mount a tour of recent construction' (most certainly the Tour Magdala) in 1905, when the floor to the Tower was finally completed in 1906 only, with the installation of its flooring by Oscar VILA in this year (as evidenced by some of the surviving invoices)?