Constructed on a small flat area halfway up a slope, over the stream of Cardona or river Negre, next to an area of fields. It was built in a strategic location, as it was common at the time.
Riner’s place is documented in 997, when Ató and his wife, Geruza, donated to Santa Maria de la Seu d’Urgell an allod located in Solsona that faced to the east with Riner. The castle is documented indirectly for the first time in 1013, in a document where Guifré de Riner confirmed that his relative, Sal•la (family of Rotrudis, wife of Guifré), had given the parish of Olesa de Montserrat to the canonical from the Santa Creu de Barcelona. Therefore two united families appear, Riner and Sal•la de Conflent, founders of the monastery of Sant Benet de Bages. Guillem de Riner died at the end of 1013, according to his will the wife of Rotrudis, in 1027, had a large number of assets located in the castles of Ardèvol and Riner, that passed to her nephew Dalmau Isarn i Riner (1026).
There was a serious conflict over the domain of the castle between the lord Ponç de Cervera and the castellan Pere de Riner, which was resolved in 1142 in an agreement (cat. convinença) between both of them, regarding their respective rights to Riner’s castle. One of the reasons for the lawsuit was a forge (fabricam) that was inside the castle’s borders, which was also mentioned in a text from 1378, which detailed that it had the bellows, anvil, mallet and hammer.
The lords of Riner increasingly showed interest towards Segarra and Conca de Barberà. Which led to them giving away their possessions in the castle of Riner, throughout the 13th century. It is said that the Count of Urgell yielded the eminent domain of this castle and of others ones in Solsonès to the viscount of Cardona for the help provided in the fight against the count of Barcelona. The Cervera family rights to the castle passed to the canonical of Santa Maria de Solsona, it is unknown how, as in 1322 Bernat de Riner castellan of the castle, paid homage to the poborde of Solsona for the castle.
It is a building with a rectangular floor plan, with a length of about 15 m, width of 8 m, height of about 18 m and 2 m thick walls. Inside, the nave, which is 11.2 m by 3.9 m and about 15 meters high, is covered with a pointed vault. The internal space was divided to at least two levels, at about 10 m from the ground there are marks of the existence of an upper floor, such as ten beam holes. On the north facade there is a door about 2 meters high by 1.8 m wide crowned by a semicircular arch formed by several voussoirs. A similar opening is on the south wall, and on the east there is a third door that leads to a staircase, inside the wall. On the north side of the fortress, towards the church, a rock valley about 4 m deep was excavated. The construction body is made of well cut and arranged ashlars, larger in size at the bottom (40 cm by 90 cm), joined with lime mortar and pebbles.
This building was most likely built in the 12th or 13th centuries. The stately building at about 5 meters to the south, is more modern, surely from the 14th or 15th century. A nave, about 11 m wide, and three arcades of which the northernmost is preserved as a whole are worth noting.