Mellingen is a historic town and a municipality in the district of Baden in the canton of Aargau in Switzerland.

Of the rest of the land, 26.7% is settled (buildings or roads) and the remainder (4.8%) is non-productive (rivers or lakes).

The compact, walled medieval city center straddles the river Reuss.

The blazon of the municipal coat of arms is "Or a Lion rampant Gules and in chief of the last a Bar[rulet] Argent.

[4] The age distribution, as of 2008[update], in Mellingen is; 475 children or 10.4% of the population are between 0 and 9 years old and 552 teenagers or 12.1% are between 10 and 19.

[9] The historical population is given in the following table:[3] The city walls are listed as a Swiss heritage site of national significance.

[9] Mellingen Heitersberg railway station is a stop of the S-Bahn Zürich on the line S11.