
Stand on the Acropolis and look east, and the horizon closes with a long, quiet line. That is Hymettus.
The mountain rises between the Attica basin and the Mesogeia plain. It runs north to south, from the Agios Ioannis Kynigos pass to the heights above Voula and Vari. Greek Wikipedia gives a length of 23 kilometres, a width of 4 to 6 and an area of 80,000 stremmata. English Wikipedia gives 16 kilometres in length and 6 to 7 in width. The figures differ depending on where you start and end counting, so we give them as approximate.

Two mountains in one. Roughly halfway, the mountain divides in two. The northern part, with the highest peak, was called Megas Hymettos (Great Hymettus) by the ancient Athenians. The southern part was called Elasson (Lesser) or Anydros (Waterless) Hymettus. Today its names are Mavrovouni and Kontra.
Peaks. The highest is Evzonas, at 1,026 metres. Next come, according to Greek Wikipedia, Mavrovouni (770 m), Stroma (735 m), Korakovouni (728 m) and Profitis Ilias (659 m).
Stone. Geologically Hymettus belongs to the Attic-Cycladic zone. Its rocks are limestone, schist and large masses of marble.

Climate. Wikipedia lists averages from November 2007 to August 2011, from the Hymettus weather station. In January the average high is 13.3 °C and the average low 8.2 °C. In July the average high reaches 33.4 °C and the average low 25.3 °C.
Routes. Marked trails exist on the mountain. Wikipedia mentions route 2 (1.9 km loop around Korakovouni) and route 3 (2.5 km loop starting from Papagou Cemetery).
Not verified: (1) The exact location of the weather station, so the temperatures do not necessarily describe the summit. (2) Road access: Greek Wikipedia says the road reaches the summit, English Wikipedia says access is limited to authorized vehicles. Check before any visit. (3) The coordinates differ slightly between the two editions, so they are not given.
Sources
- Wikipedia (Greek), Υμηττός: https://el.wikipedia.org/wiki/Υμηττός
- Wikipedia, Hymettus: https://en.wikipedia.org/wiki/Mount_Hymettus