In Marina de Cudeyo there are signifivant vestiges of medieval architecture: the castle of Agüero, ancestral seat of one of the oldest lineages in Cantabria. In the nearby town of Gajano is the tower of Riva-Herrera, halfway between being a medieval tower and a renaissance house.

South of the previous district is Medio Cudeyo. The most interesting thing about this place is its lay architecture. The palace of Valbuena, in Solares, stands out, as does the Cueto casona in Sobremazas and the palace of Torre Anaz. The tower of Alvarado in Heras is 16th century.

Continuing southwards, one reaches the district of Liérganes, one of the richest in Trasmiera in terms of heritage. The rise of this district due to the establishment of gunnery factories in the 17th century has already been outlined above. As for religious architecture, there is the church of San Pantaleón, built in the 14th and 15th centuries; the church of San Pedro ad Víncula, a beautiful example of Renaissance architecture in Cantabria; and in the nearby village of Pámanes there is the church of San Lorenzo, 16th century, with a beatiful Hispano-Flemish façade. Lay architecture is extremely interesting in this district, all of it having arisen through the wealth created by the factories, although earlier buildings are also preserved -such as Setién house, with a magnificent Plateresque window. the neighbourhoods of Mercadillo and Vitiote in Liérganes are good showpieces of 17th and 18th century classical architecture, and close by is the house of Cannons. In the Rañada neighbourhood there is the palace and chapel of Cuesta Mercadillo, known as the "Rañada palace". The neighbourhood of Rubalcaba is very interesting to visit, being the furthest from the village and situated on the way out to the mountain pass that connects Liérganes with Castile. It is an interesting baroque ensemble formed by a casona, a chapel, and two mills. In the nearby village of Pámanes the neighbourhood of Elsedo stands out, with its interesting and very well-preserved popular architecture, and the palace of Elsedo, of the 18th century, one of the best examples of palatial Baroque in Cantabria.

East of Medio Cudeyo is the district of Entrambasaguas, where extremely interesting lay architecture is preserved. In the town of Hoznayo there is the palace of Acebedo, one of the earliest palaces in Cantabria. Later examples are the palaces of Entrambasaguas (Viar, Pezuela and Hoyas) and Navajeda (Cobo de la Torre), valuable examples of Baroque architecture.

The district of Riotuerto east of Liérganes enjoyed great renown in the time of the La Cavada gunnery factories, of which only the neoclassical arch ordered by Charles III remains. There are some examples of Baroque casonas, but the more remarkable architecture her is that of the 19th century. There are various examples of residential architecture (casas de indianos, the houses of former colonists returning rich from the Americas), industrial architecture (Textil Santanderina) and sepulchral architecture, exemplified in many vaults of a high quality.

As for religious architecture the most outstanding example is the church at Rucandio, one of the very few examples of Baroque religious architecture -octagonal central plan, with an octagonal tower- in Cantabria.

The last district that remains to be described is that of Miera, situated to the south of Riotuerto and Liérganes. the best building in this locality is the church of Santa María (St Mary) in the Cárcoba area.