The castle and the settlement beneath the castle supposedly got their name after a pegan knight Meng. The name Menger or its German version Mannsburg which obviously originated from German name Meingo, Mengoz or Megingoz is mentioned in documents from 10^th to 12^th century.
First indirect mentioning of the castle (as Meingosburg) is found in 1154 when knight of Mengeš is mentioned, ministerial of Andechs, Ditrik of Mengeš (Dietricus). After 1230 the castle was a property of Friderik II., duke of Styria. Between 1248 and 1251 the castle was occupied by count Majnhard of Gorica as manager for the emperor and was followed by Spanheims. The castle was resigned in their benefit in 1250 by one of Andechs' heirs, patriarch Bertold of Oglej (Aquileia). This year the castle is explicitly mentioned for the first time as castrum Mengosburch. In 1260 vassal Ortolf of Mengeš is mentioned. Next mentioning of the castle is found in 1316 (das haus datz Meyngospurch); at the time Hartvik Steier (of Styria) gave his half of the castle (half was owned by Friderik) to his wife and sons. In 1329 Hertlein received third of the castle to fee from duke Henrik which formerly belonged to sons of Friderik Steier. Friderik's widow Trauta with sons sold part of the other half in 1335 to Hartlein and Henrik from Ortolf's lineage (ainen tayl von unserm tayl) and some parts were sold to them earlier by their relatives. Also castle hill, defence walls, inner ward ond other were sold. Friderik's branch finally sold its part in 1337 to Hartwik's branch. For genealogical overview of branch of lords of Mengeš see Kos: Vitez in grad. In 1345 Hartwik left the castle to his relative Rajnher Schenk from Ostrovica and he already in 1356 sold the castle to Egelolf Müllingerj. It is possible that at the time the ownership was divided and the other owners were lords of Mengeš from Ortolf's lineage. Later as the castle owner also appear Johan from, Peggau, lords Gallenbergs and lords Hohenwarts. The latter abandoned the castle in 17^th century and approximately between the years 1625 and 1630 at the foothills of castle hill built a new headquarters of dominion.

Lords of Mengeš used as many as three different coat-of-arms in 14^th century. First was coat-of-arms used by brothers Ortolf and Wisent (from Krško) from the end of 13^th or the beginning of 14^th century with split shield and empty right field and three rafters in the left. All their sons used coat-of-armes with interweaved hooks. All of Wiset's sons went to work for counts of Gorica and received Mehova to manage. Third coat-of-arms which was used by Hartwik's (one of Wiset's sons) branch had a growing lion above two wave-lines or obliquely divided shield with upper lion half in the first field and wave-lines in the other.

Mengeš castle was never depicted in the period of its existence. Topographical sketch by architect Peter Fister is the only source from where we can learn at least something about its former design. Its publising was acompanied by a text which mentions two plateaus overgrown by sod, divided by three defence moats but remains of walls can be only seen on larger, northern, partially secondarily leveled plateau and on the southern remains of church of St.Lovrenc are still partially preserved. Also mentioned in the report are foundations of semicircular building next to the church for which I think are the remains of some younger, additional, undoubtfully Renaissance era fortification.

In a book Vitez in Grad (Kos) and Vsi slovenski gradovi(Jakič) we can find a picture of a tower from before the reconstruction works.