As usually happens in this type of installation, it is a small building arranged perpendicular to the river current, in this case the Unhòla, on the right bank, with the door located at the opposite end and the main facade on the south side, sheltered by a double-sided roof. A derivation lock or fish tank fed a fairly long channel parallel to the river bed that enters the building on the north side and exits through a gabled arcade (1.30m clear); the hydraulic force moved the two wheels it had. The entrance door has an inscription above it: J.M// AÑ 1806, and in front two floating stones have been used as tables. The interior retains much of the old machinery.

An early agreement between the prohoms of Unha established “that those from the party below populate the Molar Mohedir itself” (1278). La Mòla d’Unha is recorded in the 1717 Cadastre, the lease of which produced good municipal income. Similarly, there is a flour mill in the year 1789 in the questionnaire of Francisco de Zamora (answer no. 118) which highlights the production of all kinds of cereals.