Colle di Zambla (1,264 m)

It is natural to think so, but the explanations differ. Wikipedia writes that the name describes a village reached from either valley by crossing a pass. The municipality of Oltre il Colle tells another story: it was the people of Serina who gave this name to the lands they saw beyond the Forcella di Valpiana and the Col d'Anì, the natural boundary between Serina and Oltre il Colle. The local historian Massimo Maurizio, quoted by the Blog della Valserina, agrees: the reference is not to the Colle di Zambla but to the Col d'Anì.

A 2008 article in L'Eco di Bergamo offers a third reading, from the opposite side: those who came from the Seriana valley, drawn by the mines, found the municipal territory precisely beyond the watershed. In the oldest documents the village appears as Ultracollum, for example in the statutes of Bergamo of 1491. The Colle di Zambla does in any case give its name to the two hamlets at its foot, Zambla Alta and Zambla Bassa.

On the Seriana side you start from Ponte Nossa, at 450 metres, and climb the whole Val del Riso on provincial road 46, through Gorno and the hamlets of Oneta: according to Wikipedia it is a 14.1-kilometre winding climb, with a maximum gradient of 10 per cent and no shade on the last stretch. On the Brembana side the road is provincial road 27 of the Val Serina: it starts at Ambria, a hamlet of Zogno, at 330 metres, runs through Algua, Serina and Valpiana, enters the upper Val Parina and passes Oltre il Colle and Zambla before the pass. It is a long climb, 23 kilometres, with false flats between the steeper sections, which never exceed 11 per cent.

The table below gives the CyclingCols figures, which measure 14.0 kilometres from Ponte Nossa and 23.2 from Ambria. In summer 2026 the Val Serina provincial road was closed from 28 August to 1 October after a large boulder fell at Rosolo di Algua, with traffic diverted onto the Costa Serina road: it reopened on the afternoon of 1 October.

The pass has been included twice in the Giro d'Italia, in the mid-1970s. In 1976 it was tackled by the twenty-first stage, on 11 June, from Terme di Comano to Bergamo: Gianbattista Baronchelli was first over the top and the stage was won by Felice Gimondi. The following year, on 9 June 1977, it was the turn of the nineteenth stage, from Pinzolo to San Pellegrino Terme: Renato Laghi crossed the pass first and also won at the finish.

For today's cyclists the Val del Riso side is the shorter and more regular, the Val Serina side the longer. CyclingCols gives 806 metres of height gain at an average 5.8 per cent for the eastern side, and 958 metres at an average 4 per cent for the western side.

Before the road there was a mule track linking the communities of the two valleys. According to research by the local historian Massimo Maurizio, reported by the Blog della Valserina, on the Seriana side it climbed steeply up the slopes of Oneta and was poorly suited to heavy loads, while links with Bergamo went through the easier Val Serina; the road that crosses the pass would only have been opened around the 1970s. In the Val del Riso, however, a carriage road already existed in 1884: the municipality of Gorno asked the English mining company Crown Spelter to pay for its upkeep, because it was being ruined by carts loaded with ore.

The pass was also a mining boundary. After 1922 Vieille Montagne divided the Bergamo concessions into a Seriana valley group, east of the line between the Crocetta and the Sinelle at the Colle di Zambla, and a Brembana valley group to the west; underground, the Riso-Parina tunnel linked the Val del Riso to the Val Parina. On the Val Serina side the connection with the city ran on wheels instead: on 25 November 1944, during the round-up that ended with the Cornalba massacre, fascist militiamen stopped the scheduled Zambla-Bergamo bus just before Rosolo.

Five minutes from the car park on the pass, following CAI trail 238 northwards, you come to the small church of the Madonna di Caravaggio, at 1,251 metres. The diocesan survey describes it as an eighteenth-century chapel lengthened by one bay in the nineteenth century, with on the altar a canvas of the apparition of Caravaggio commissioned in 1937 by the Benvenuti family, who owned a holiday home in Zambla Alta: a small sign of the summer holidays that were already bringing people up to the mountains.

Trail 238 continues to the Cascine Sinelli, the Baita di Monte di Zambla and the Baita Camplano, at 1,830 metres, which the CAI puts at 2 hours 15 minutes from the start, and reaches the Capanna 2000 in about three hours. Stages 6 and 7 of the CAI's Sentiero dei Laghi Basso, from Serina and towards Clusone, also pass through, and routes to Monte Alben and the Grem set off from here.

In winter the pass is a starting point for cross-country skiing, while downhill skiing in the basin is now history: a lift in the Conca dell'Alben had been idle since 1988 and in October 2012, L'Eco di Bergamo reported, the municipality had its last six pylons taken down, together with the three remaining from the Arera ski lift, which had worked until the 1990s.