The municipal territory of Algua with the main village extends along the right bank of river Serina. The route of the Mercatorum Way, arriving from the Ambriola Valley, therefore runs along this slope, connecting a number of hamlets halfway up the hillside, such as Pagliaro and Frerola, then descending again to the bottom of the valley and entering the municipality of Serina at the bridge over the Valle Scura valley. The route alternates between asphalted, but low-traffic sections of road (except for the final stretch on the SP 27 provincial road), and stretches of ancient pedestrian paths.