It is a free building that was constructed with ashlars carelessly cut. It has a nave of section covered with a forged with logs to two waters that are left sights. This forging has been reinforced by a pillar that is near to the presbytery in the axis of the nave.

Other two pillars of octogonal section frame the entrance of the choir and they also serve like a strongpoint of the cover. The choir is on the feet of the nave in an more elevated plane. It is separated by an artisan wooded balustrade.

The cover is in the wall of the epistle. In it there is a simple arch of voussoirs with the imposts slightly raised and a coat of arms. There is an inscription that says: " this church was rebuilt in year 1.898 thanks to the Ilmo. D. Mariano Supervía, bishop of Huesca "

The church has an only vane in the side of the feet. In the head of the church, next to the vestry, there is a steeple of ashlar masonry.

This church is dedicated to Sanit Ann.

The 30 of July of year 2.000, a mass was celebrated in this church to celebrate the festivity of Sanit Ann, the pattern of this town. Although the town is totally vacated, great number of parishioners of Ayerbe and Region, in addition to great number of neighbors who formerly lived in Fontellas went there that day. Everybody remembered the splendor of the town years ago. Since then and due to the good welcome the idea had, this mass is going to be celebrated every year.