Lohmar is located about 20 km east of Cologne and 15 km north-east of Bonn in theBergisches Land area. Because it is only 20 minutes by car toCologne orBonn, Lohmar is a popular place forcommuters.
The municipality of Lohmar is divided into two parts: Lohmar itself and Wahlscheid 7 km to the north. About a third of the total population lives inWahlscheid (a separate municipality until 1969). In total Lohmar comprises 30 districts. The most important are Lohmar itself (est. population approx. 9500),Donrath (2200), Heide (2100) and Birk (1400) in the south, as well as Wahlscheid (3200), Neuhonrath (2000), Honrath (1500) and Agger (1000) in the north.
Lohmar, Donrath, Wahlscheid, Neuhonrath and Agger are located in theAgger valley, the other villages in the uplands.
Lohmar was first mentioned as a donation of archbishop Sigewid to the church of Cologne. A farmyard inLomereis mentioned.
Lohmar is also mentioned on theArc de Triomphe in Paris as a place ofNapoleon's visit. While his inspection of the army positioned in theRhineland in 1811 he lived inSchloss Auel in Lohmar.
Thecoat of arms contains a lion of Berg in the upper fragment. It symbolizes the former jurisdiction by theEarldom of Berg. The lower fraction shows the meeting of theAgger and theSülz rivers.
Lohmar is served byHonrath railway station on theCologne–Overath railway. A train to Cologne stops every 30 minutes. The trip to Cologne lasts about 30 minutes. A service runs in the other direction toOverath every 30 minutes.