Lake Iseo marks the boundary between Bergamo and Brescia and, apart from being an economic resource for the local population, from the Middle Ages it represented an area of political confrontation. It was, in fact, the point in which the contrasts between the two townships manifested themselves to the full, especially in the northern part of the lake for the control of the commercial traffic coming from Valle Camonica, and in the south where disputes arose regarding the jurisdiction of the land by the Signoria of Calepio. Monte Isola, in the centre, was in contact with these two realities being in a position to control the traffic on the lake especially through the canal of Tavernola.

The different politics were accompanied by different forms of settlements and architecture: on the Bergamo side of the lake, in fact, fortified buildings were erected in a mountainous and rather harsh pre-Alpine context; on the eastern side of the lake , on the contrary, the centres developed in hilly areas where strongholds were not always built.

As far as the ecclesiastical organisation was concerned, the Brescia side of the lake was divided between the ecclesiastical circumscriptions of Iseo and Sale Marasino which was joined, from the 11th Century by Pisogne. The Bergamo side of the lake  was divided between Calepio and Mologno (the present day Casazza in Val Cavallina), which was later replaced by the ecclesiastical circumscription of Solto, founded in the 12th Century for the pastoral care of the northern side of Lake Iseo. This situation led to a fragmentation of power that emerged during the 12th Century when the municipalities organised themselves within the boundaries already defined by the ecclesiastical circumscriptions.

On the Brescia side, the northern part of the lake part was under the control of the bishop from the 10th to the 11th Century with the support of the monasteries, especially that of Santa Giulia which owned land on the shores of the lake.

From the 10th Century, Iseo was the location of a market and the commercial hub on the boundary, facts that aroused the interest of the municipality of Brescia. The centre was governed both by the bishop who underlined his political dominance with the monumental baptismal church of Sant’Andrea, and by the local Signorie together with the middle merchant class (Brusati, De Iseo/Oldofredi) that encouraged the development of residential buildings.

The castle of Iseo, which was erected on the site of a pre-existing tower and was then modified between the 13th and the 14th Centuries with a curtain wall and towers with a side open towards the inside, represented the strategic stronghold for the military defence of the borgo. Iseo was involved in the wars of the municipality of Brescia and in 1161 suffered a devastating siege and fire at the hands of Federico Barbarossa.

Other defence buildings demonstrating the power of the Signorie can be found near Paratico: the local castle and the Lantieri tower symbolise the importance achieved by this family which existed side-by-side the rural secular Signoria of the De Paratico.

On the contrary, the religious and civil power co-existed in nearby Clusane where a castle was situated from the end of the 11th Century while the monks of Cluny settled on the promontory where they founded a priory (that was later entrusted to the nearby monastery of Provaglio d’Iseo). The rise of the Signorie of the Isei/Oldofredi led, in the 14th Century to the construction of the Carmagnola Castle, which was later encircled by a wall with a drawbridge.

Also in the hands of the Oldofredi of Iseo was Monte Isola which was occupied at the foot of the hills by the monastic estates of Santa Giulia, records of which date back as far as the 10th Century. Between the 12th and 13th Centuries, the Oldofredi of Iseo commissioned two defence fortresses: the mighty tower at Siviano, and the castle in Menzino located in a strategic position for the control of the Bergamo side of the lake; another castle belonging to the Oldofredi can be found in Peschiera  Maraglio, on the southern tip of the island looking towards the Brescia side of the lake.

In Marone, on the other hand, the population took refuge in the foothills where a small fortress was situated in Pregasso that was later destroyed in the 17^th Century: this area too became the stronghold of the Oldofredi, faithful allies of the Visconti until the arrival of the Venetians.

The situation was different, however, on the western side of the lake: in the south, the territory was governed by Sarnico, a village under the pro-Brescia Signoria of the Calepio, which ran an autonomous policy compared with the municipality of Bergamo. This position led to the construction of a greater number of fortified buildings compared with the opposite side of the lake, underlining a  local deeply rooted power of the Signoria.

Scattered settlements were established midway along the coast, from Predore to Tavernola and were convenient for the economic exploitation of the territory: this polycentrism prevented the development of demographically important centres. Such an organisation lasted until the 14th Century when the lengthy persistence of the Signorie gave way to small demographic groups that referred to just one parish benefice. This area lacked a strong political power and the families of the Signorie demonstrated their presence on the territory by building towers and tower-houses in the villages (as did the Fenaroli family in Tavernola, Vigolo and Parzanica).

The absence of a strong comital power is evident in the lack of imposing fortified buildings, with the exception of Zorzino, unlike the Brescia side of the lake. On the Bergamo side of the lake mainly isolated towers are found like those of Predore and Tavernola.

Numerous towers were erected in Riva di Solto, Solto Collina and Castro to defend the areas under the authority of the Signorie. These villages were united, since the 13th Century, under the control of the Foresti family which had been established there by the municipality of Bergamo to deprive families with episcopal lineage of their authority. The architecture bore witness to the importance of the local Signorie, presenting a social role as well as a sign of the economic well-being they had achieved.

Finally, in the northern part of the lake, a completely different situation existed: Pisogne, Costa Volpino and Lovere were the scene of violent clashes between Bergamo and Brescia for the monopoly over the commercial traffic on the lake. Pisogne, which controlled the commercial routes from Valle Camonica, was the feud of the bishop of Brescia and assumed the political role of head of the Curia: in 1119 it was destroyed after being involved in a war between Bergamo and Brescia for the control of Volpino; it was subsequently rebuilt at the wish of the bishop who provided it with town walls, defensive towers and doors, including the so-called Torre del Vescovo.

The episcopal power spread from Pisogne towards Lovere which was controlled by the municipality of Bergamo, but was under the bishopric of Brescia: here various fortified buildings were erected, including the castle of the Celeri, a local noble family, the Zucca tower and the Alghisi tower, the residences of important local families and the Tower of the Porto to control access to the lake.

Another strategic location which was disputed between Bergamo and Brescia was Costa Volpino, an area under military protection controlling the Valle Camonica and the mouth of the river Oglio: documents describe the dungeon and the tower of the castle of Volpino, suggesting it was a complex and imposing fortified building. The castle was the subject of great contention until peace was established in 1192, but here the Brescia politics would be unsuccessful in the face of a solid system of lordly power which, although on the side of Brescia, was moving towards progressive autonomy and the ambitions of the municipality of Bergamo that had never been assuaged. Not even the foundation by the municipality of Brescia of the free village of Castelfranco between Rogno and Costa Volpino (1255) would allow Brescia to play a key role in the politics of the valley.

Federica Matteoni