Na wzgórzu farnym znajdował się gród kasztelański. Gród funkcjonował już w XI w.1
Pierwszy kasztelan ciechanowski jest poświadczony przez dokument, w którym książę Siemowit I
nadaje biskupowi płockiemu wieś Proszkowo z 1 254 r.2, jest nim Rathiborius.
Z XIV w. pochodzi pierwsza wzmianka o parafii ciechanowskiej. Kościół parafialny został
wzniesiony na wzgórzu farnym w pobliżu grodu kasztelańskiego. Był to kościół drewniany a od
XVI w., murowany (Pseudobazylika). W połowie XIV w. Ciechanów otrzymał prawo targu a w roku
1400 prawa miejskie.
Ciechanów is one of the medieval towns of northern Mazovia.In 1400, its town rights were granted and the town quickly rose to become one of the most important in the Duchy of Mazovia.The term „Ciechanów mystification" in the study is a reference to falsifications, which were committed by Jerzy Gaczynski, it is the allegedly fifteenth century „annals", whose author was supposed to be Stanislaw from Lipia, as well as the others documents, such as the cited text Ciechanów (1266), which were included with the „annals" in the volume Liber Ecclesiae Praeposi- turalis Ciechanoviensis in the parish archives of the Parish Church in Ciechanów.The alleged disclosure of „Ciechanów annals" was presumably accomplished by Jerzy Gaczyński.In the early 90s of the twentieth century, Henryk Rutkowski established that the "annals" were a twentieth-century forgery written by J. Gaczyński.Unfortunately, both documents related to the mystification were published in NKDmaz II, there are documents 49a, which were supposed to be the location text Ciechanów from 1266 and document 98, so the alleged summary of the confirmation of Bolesław II for St Peter's Church in Ciechanów from 1295.