In the past the village was called Sant'Ambrogio di Grion, a name which still survives in ecclesiastic administration. While there is no doubt that "Sant'Ambrogio" (Saint Ambrose) refers to the bishop of Milan who lived in the 5th century A.D, there are many educated guesses regarding the place name "Grion". One makes it derive from Monsignor Gregorio Giustiniani, who was at the head of the dioceses in the 12th century, while another puts it in relation to the Venetian family of the "Grioni". A third hypothesis is proposed by Dante Olivieri in the most important repertoire of Venetian place names from 1919, where he makes the word "Grion" derive from the person name "Graecone", meaning "greek". The place name is to be found also in Friuli Venezia Giulia, in documents from the 13th century, in the form "Grigions". "Grigions" could have a Celtic origin and it would indicate an heath bush.
The history of Sant'Ambrogio during the late period of the Roman Empire and the High Middle Ages is common to that of the old X Regio (10th Region) - Venetia et Histria - characterized by continuous and devastating barbaric raids, the last one being that of the Hungarians.
The area where Sant'Ambrogio is situated has always had an agricultural character because during the Roman Empire it was between 20 and 30 km far away from the nearest towns - Altinum, Tarvisium and Patavium, and even further from the town of Acelum. The most magnificent and lasting Roman monument, which is still present in this territory after 2000 years, is the centuriation - the division of the land in squares (scamna), which were destined to the Roman veterans. It is the Roman centuriation of the "Agro di Altino", which is situated to the west of the river Sile (Silis flumen) and which was realized probably in 49 B.C.
The presence of a "castrum" (castle) in Sant'Ambrogio di Grion almost certainly already from the Roman era bears testimony to the economical importance of this place for the cereal production and later on, during the Middle Ages, also for strategic reasons as Sant'Ambrogio was a boarder territory between the lands of the Bishop-count of Treviso, the territories of the Carraresi, lords of Padua and those of the Serenissima Republic of Venice, future ruler of the Veneto Region.
The Castle of Cigotto is attested since the 12th century in the papal bull of Pope Eugene III of the year 1152 A.D. This document quotes amongst the possessions of the Bishop-count of Treviso even the "Pieve of Trebaseleghe with the castle [...] and the castle of Sant'Ambrogio". Some mentions of the castle with a military function are to be found up to the 12th century, and from that moment on it fell into ruin. Some traces of the existence of the castle are to be found up to the 19th century, when the Veneto region was part of the Austrian empire. In the maps of the Austrian cadastre from 1845 a place name called "Le Motte" indicates a small hill with defensive purpose. The castle was in the "regola1" of Sant'Ambrogio on the boarders with the "regola" of Grion.
During the Middle Ages, firstly governed by the vassals of the Holy Roman emperor, the cities of the Veneto region organized themselves in free "Comuni", which often became allied against the Holy Roman Empire - in order to become free from its control. Likely often they were at war with each other, and it is in this scenario that Sant'Ambrogio di Grion was disputed by the lords of Padua, Treviso and the Venetian doges, and during some periods also by the border violations of the Scaligeri family of Verona and by the expansionist politic of Ezzelino da Romano. All of this meant plunders, destruction, abuses and massacres and famine for the local population. The last and fatal blow to the castles of Trebaseleghe and Sant'Ambrogio was given by the terrible Ezzelino da Romano. From that moment they remained in ruin and they lost their military importance, in favour of the neighbouring town of Noale. To reunite again a great part of nort-east Italy under one government was the Republic of Venice between the 14th and the 16th century. During this period, apart from the war against the League of Cambrai, the Republic assured the peoples of north-east Italy and consequently of Sant'Ambrogio more than 300 years of peace and prosperity.
The history of Sant'Ambrogio and of the Veneto region from the end of the 18th century up to the beginning of the 20th century are characterized by foreign occupations, first that of Napoleon and of the French army, who, ignoring its neutrality, invaded and plundered the Republic of Venice, just to leave it to the Austrians and to take it back again up to the Congress of Vienna, which handed it over to the Austrian empire for good.