"Addua" redirects here. For the moth genus formerly known as Addua, see Dysschema
The Adda (Latin Abdua, or Addua; in Lombard Ada) is a river in North Italy, a tributary of the Po. It rises in the Alps near the border with Switzerland and flows through Lake Como. The Adda joins the Po a few kilometres upstream of Cremona. It is 313 kilometres long. The highest point of the drainage basin is the summit of la Spedla (a subpeak of Piz Bernina), at 4,020 m.
Towns along the river Adda include Bormio, Sondrio, Bellagio and Lecco (both on Lake Como), and Lodi.
The Adda's true source is in some small lakes near the head of the Fragile glen, but its volume is increased by the union with several smaller streams, near the town of Bormio, at the Raetian Alps. Thence it flows first southwest, then due west, through the fertile Valtellina, passing Tirano, where the Poschiavino falls in on the right bank, and Sondrio, where is the junction with the Mallero, also on the right. It falls into the Lake of Como, at its northern end, and mainly forms that lake. On issuing from its southeastern or Lecco arm, it crosses the plain of Lombardy where it is joined from the left by the Brembo, Serio, and finally, after a course of about 240 km (150 mi), joins the Po, 13 km (8 mi) above Cremona.
The 1377 erected Trezzo sull'Adda Bridge remained with a world record span of 72 m the longest bridge arch to have been built before the introduction of metal into bridge construction. The lower course of the Adda was formerly the border between the Republic of Venice and the Duchy of Milan, after the Treaty of Lodi, 1454; and on its banks several important battles have been fought, notably that of Lodi, where Napoleon defeated the Austrians in 1796; several battles have also taken place at the bridgehead of Cassano d'Adda.
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.
Coordinates: 45°08′04″N 9°52′54″E / 45.13444°N 9.88167°E