Brugg (sometimes written as Brugg AG in order to distinguish it from other Bruggs) is a Swiss municipality and a town in the canton of Aargau and is the seat of the district of the same name. The town is located at the confluence of the Aare, Reuss, and Limmat, with the Aare flowing through its medieval part. It is located approximately 16 kilometers (9.9 mi) from the cantonal capital of Aarau; 28 kilometers (17 mi) from Zürich; and about 45 kilometers (28 mi) from Basel.

Brugg is the Swiss German term for bridge (German: Brücke). This is an allusion to the purpose of the medieval town's establishment under the Habsburgs, as the town is located at the narrowest point on the Aare in the Swiss midlands. The Habsburgs’ oldest known residence is located in the neighborhood of Altenburg, which had previously been an independent community. Prior to their relocation to Austria, Brugg was the center of the Habsburgs' territory. Between 1415 and Napoleon’s invasion in 1798, Brugg was a subject territory of Bern. Since then it has belonged to the canton of Aargau.

The town is the home of the Swiss Farmers’ Union and is the location of a campus of the University of Applied Sciences and Arts Northwestern Switzerland. Brugg's Vindonissa museum is listed as a heritage site of national significance. An engineer training unit of the Swiss army is also based in the town.

The municipality extends for six kilometers (4 mi.) from its southwestern to northeastern boundaries, and is barely wider than one kilometer (2/3 mi.) at its broadest point. The Aare, which flows through the centre of the old town, divides the municipality into two separate, distinct landscapes – the Swiss plateau on the southern bank and the beginnings of the Jura on the northern side.

The southwesternmost area of Brugg is primarily a flood plain, known as the Wildischachen, which is located between the Aare and a hill, the Wülpelsberg, upon which the Habsburg castle in the neighboring community of Habsburg was built. Approximately two kilometers (1.25 mi.) further north two separate branches of the Aare come together near the village of Altenburg. In between these two branches, which came into being following the construction of the hydroelectric power station Wildegg-Brugg, is the forested island of Schacheninsel.

Following a bend in the river, at which it alters its course from the north to the east, the river enters a 200-meter-long section with a rapids and a (650 ft) gorge. The Aare narrows from its previous width of about 130 meters (430 feet) to a mere 12 m (39 ft). It is along this gorge that the historic center of Brugg formed near the old bridge, with sections of the old town developing on both banks. Today the southern bank is heavily built up and is composed primarily of residential and industrial buildings, while the northern bank, due to the lack of space at the foot of the Bruggerberg (516 m (1,693 ft), is less settled.

The Aare broadens again after it exits the gorge and departs the old town, where it flows alongside the Aufeld plain. A majority of the population in this area is concentrated in a small band along the southeastern slope of the Bruggerberg. On the eastern border of the municipality three of the most important Swiss rivers flow together, first the Reuss and the Aare, the combination of which is met approximately one and a half kilometers (0.93 miles) further downstream by the Limmat. In the northeasternmost part of town, nestled between the mouth of the Limmat and the Reinerberg (522 m (1,713 ft) is the village of Lauffohr, which also is a part of Brugg.

Brugg has an area, as of 2007^[update], of 5.56 square kilometers (2.15 sq mi). Of this area, 0.74 square kilometers (0.29 sq mi) or 13.3% is used for agricultural purposes, while1.58 square kilometers (0.61 sq mi) or 28.4% is forested. Of the rest of the land, 2.79 square kilometers (1.08 sq mi) or 50.2% is settled (buildings or roads), 0.38 square kilometers (0.15 sq mi) or 6.8% is either rivers or lakes and 0.03 km² (7.4 acres) or 0.5% is unproductive land.