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 (194 mi) long. The highest point of the drainage basin is the summit of la Spedla (a subpeak of Piz Bernina), at 4,020 metres (13,190 ft).
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 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 kilometres (150 mi), joins the Po, 13 kilometres (8 mi) above Cremona.
The River Adda is a small watercourse which flows, for the most part culverted, through the city of Bangor North Wales before discharging into the Menai Strait at Porth Penrhyn. The name is said to be of 19th-century origin, deriving from a field Cae Mab Adda (the field of the son af Adam) close to its source. Its earlier name was Tarannon.
Coordinates: 53°13′47″N 4°06′40″W / 53.22972°N 4.11111°W / 53.22972; -4.11111