Lombardy is a historic region of Italy and one of the 20 regions of Italy. The capital is of the region is the city of Milan. A sixth of Italy's population lives in Lombardy and about a fifth of Italy's GDP is produced in the region, making it the most populous and richest region in the country. It is also the region with the most Unesco World Heritage Sites in Italy. Lombardy originally referred to the entire territory of Italy (known as Longobardia Major and Langobardia Minor) ruled by the Lombards, a Germanic tribe who conquered much of the Italian peninsula beginning in the 6th century.

Lombardy is bordered by Switzerland (north: Canton Ticino and Canton Graubünden) and by the Italian regions of Trentino-Alto Adige/Südtirol and Veneto (east), Emilia-Romagna (south), and Piedmont (west). Three distinct natural zones can be fairly easily distinguished in the Lombardy region: mountains, hills and plains – the latter being divided in Alta (high plains) and Bassa (low plains). The most important mountainous area is an Alpine zone including the Lepontine and Rhaetian Alps, (Piz Bernina – La Spedla, 4,020 m), the Bergamo Alps, the Ortler Alps and the Adamello massif; it is followed by an Alpine foothills zone Prealpi, which include the main peaks are the Grigna Group (2,410 m), Resegone (1,875 m) and Presolana (2,521 m). The great Lombard lakes, all of glacial origin, lie in this zone. From west to east these are Lake Maggiore, Lake Lugano (both shared with Switzerland), Lake Como, Lake Iseo, Lake Idro, then Lake Garda, the largest in Italy. South of the Alps lie the hills characterized by a succession of low heights of morainic origin, formed during the last Ice Age and small barely fertile plateaux, with typical heaths and conifer woods. A minor mountainous area lies south of the Po, in the Apennines range.

The plains of Lombardy, formed from alluvial deposits, can be divided into the Alta – an upper, permeable ground zone in the north and a lower zone characterized – the Bassa – by the so-called line of fontanili (the spring waters rising on impermeable ground). Anomalous compared with the three distinctions already made is the small region of the Oltrepò Pavese, formed by the Apennine foothills beyond the Po River. A large number of rivers, all direct or indirect tributaries of the Po, cross the plains of Lombardy. Major rivers, flowing NW to SE, are the Ticino, the outlet of Lake Maggiore, the Olona, the Lambro, the Adda, outlet of Lake Como, the Mincio, outlet of Lake Garda, and the Oglio, the Lake Iseo outflow. There is a wide network of canals for irrigation purposes. In the plains, intensively cultivated for centuries, little of the original environment remains. The rare elm, alder, sycamore, poplar, willow and hornbeam woods and heaths are covered now by several protected areas. In the area of the great Alpine foothills lakes, however, grow olive trees, cypresses and larches, as well as varieties of subtropical flora such as magnolias, azaleas, acacias, etc. The mountains area is characterized by the typical vegetation of the whole range of the Italian Alps. At a lower levels (up to approximately 1,100 m) oak woods or broad leafed trees grow; on the mountain slopes (up to 2,000–2,200 m) beech trees grow at the lowest limits, with conifer woods higher up. Shrubs such as rhododendron, dwarf pine and juniper are native to the summital zone (beyond 2,200 m). Lombardy counts many protected areas: the most important are the Stelvio National Park (the largest Italian natural park), with typically alpine wildlife: red deer, roe deer, ibex, chamois, foxes, ermine and also golden eagles; and the Ticino Valley Natural Park, instituted in 1974 on the Lombard side of the Ticino River to protect and conserve one of the last major examples of fluvial forest in Northern Italy.