That there were settlers in the Felsberg region as long ago as the last ice age is witnessed by the find of the 12,000-year-old so-called Rhünda Skull. In the first century, the Felsberg area was inhabited by the Chatti, a Germanic people. The only mention of the area from this time is a report about one of Germanicus's campaigns, when in the year 15 he destroyed Mattium (nowadays Maden), the Chatti's capital.
In the 8th century, the Felsberg region was part of the Frankish Empire, and this is when the town had its first documentary mention. It was also in this time that Christian missionary work was being done in the area by Saint Boniface, who in 723 felled Thor's Oak near Fritzlar, about 15 km west of Felsberg, thereby starting the Christianization of the peoples of northern Germany.
Within the town's municipal area lie the ruins of three castles, the Felsburg, the Altenburg in the constituent community of the same name, and the Burg Heiligenberg above the constituent community of Gensungen on the river Eder's opposite bank. The town is thus sometimes known as the Drei-Burgen-Stadt ("Three-Castle-Town"). The castles were built for their strategic location in the Middle Ages between the Archbishopric of Mainz and the Landgraviate of Thuringia, or Hesse. The Heiligenburg belonged to Mainz. Both the Felsburg and the Altenburg 2 km away are distinguished by their "butter churn" towers. The Salzstraße ("Salt Road") ran through Felsberg from the river Werra, where the salt was mined, to the Rhineland.
In 1090, Felsberg was mentioned in a Mainz document under the name Velisberc, and again under the same name in 1209 in a goods directory from the Petrus Estate in Fritzlar. Felsberg's first documentary mention as a town came in 1286. The historic town core was once surrounded by an 830-m-long town wall, only parts of which are preserved today
The Thirty Years' War brought widespread destruction to Felsberg.
|SPD||: 20 seats|
|CDU||: 9 seats|
|Greens||: 2 seats|
|FDP||: 2 seats|
|FWG (citizens' coalition)||: 2 seats|
|DFB||: 2 seats|
The town executive (Magistrat) consists of 14 councillors and the mayor. Of those, 8 seats are held by the SPD, 3 by the CDU and one seat each by the Greens, the FDP and the FWG.
Heraldically, the arms might be described thus: Party per pale gules and argent, thereover a bend sinister vert, therein three trefoils argent.
It also has friendship agreements with these places: