Bosa, the most important centre in Planargia, is a picturesque town situated in an important position along the banks of the River Temo. It offers visitors coming from Macomer a fascinating and scenic view. When the Malaspina's castle was built (year 1112) the city moved to the opposite bank of the Temo. The new town grew up all around the castle, on the slop of the hill Serravalle. There the quarter "Sa Costa " was built by the inhabitants of Bosa Vetus. The Temo, Bosa's soul, is the only navigable river in Sardinia. Since the ancient times, it has represented an economic resource and a danger too for its unavoidable flooding. The riverside, together with the middle aged quarter 'Sa Costa', the tanneries and many beautiful churches are the symbols of the eternal charm of Bosa