The borders of the historic Warmia go to the west reaching the Vistula Bay, Lake Drużno in the south and the Pasłęka River going towards the east of the Lithuania border. They were delimitated by the Pope’s legate, Wilhelm of Modena, in the document from 1243. On the strength of it, three dioceses (of Pomerania, Sambia and Warmia) came into being. Fixing the borders of the new dioceses was connected with conquering and christianisation of the lands of the pagan Prussians. The name Warmia came from the Prussian tribe, Warmowie, living from the VI century in the area of the previous administrative district Braniewo. Going further the tribesmen took their name from a city called Warmia with was placed close to Frombork.
The historic Warmia, much bigger then, was also inhabited by the tribes of Pogezanie, Nagatanie, Bartowie, Galindowie. At the end of the XII century the tribes kept fighting with one another. It was ceased by the conquest of the Teutonic Order. The first crusade was prepared in 1234. It was assisted by Polish and German knights who were sent by the Pope. The united Prussians were trying to defend themselves but they were finally defeated in 1283. The country was colonized and people were exterminated or assimilated. The conquered area was divided into three dioceses. 2/3 of each of them belonged to the Teutonic Order, 1/3 to a bishop and a chapter. The part of the Warmia belonging to the church was situated in the middle of lands which belonged to a chapter (Frombork, Pieniężno, Olsztyn). The rest of them belonged to a bishop. He was also a sovereign of Warmia. Although the clergy were economically independent, they were politically subordinated to the Teutonic Order.
The seat of Bishop was in Braniewo, where, in the middle of the XIII century, the first wooden cathedral was built. After the church had been destroyed by the Prussians, the capital of the diocese was moved to Frombork which was placed nearby. The settlement located on the outskirts of Warmia bordered the lands belonged to the Teutonic Order through the River Narusa. That is why people living there felt secure as far as the Prussians were concerned. The secular capital of Warmia since 1380 was Lidzbark, where bishops owned real mansions. On the other hand the spiritual capital of the diocese was Frombork.
Frombork had already been settled when church arrived. There is a legend connected with a foundation of the town. The lady of the city, Supona, also called Plastwig, gave her property to a parish-priest of the chapter. Nobody knows whether the city was placed in Frombork, but the name of the city: Castrum Dominae Nostrae and German name Frauenburg (in polish Frombork) probably comes from the legend as it may mean the city of a lady.
Bishop Henry I transferred a seat of the diocese in the years 1270-1278. As a name Civitas Frowenburg is found in a document from 1278, it is very probable that the settlement had already existed there. It was necessary to assign a suitable estate at the sacrifice of the areas given to the city. When a few canons arrived in Frombork, according to the Lubeckie Low, the official location of the city took place not before 8 July 1310 by bishop Eberhard, after the contention with conferment between the chapter and the municipal government had been ended.
The city which belonged to the district of Frombork was governed by an administrator, usually one of the canons. The town did not posses much ground and apart from that it not only was deprived of a part of its privilege but was also charged with a huge rent. That is way the town was developing very slowly. Moreover Braniewo and Elbląg tried to defend their trade position and they did not let the city to create a trade port. The fishing port came into being in the city about the middle of the XV century.
Frombork surrounded only by a palisade was an easy plunder and an important aim as the capture of the city would give a possibility to control the Vistula Bay and the water route from Malbork to Królewiec.
The great number of wars which took place in the Middle Ages and in modern times devastated the city for many times. For the first time it happened in 1414 when King Jagiełło burnt the city and robbed the cathedral during the war called “a war of hunger”. During the 13-year-war canons were made to opt for the Association of the Pruss by the citizens of Braniewo. In return the commander Plauen burnt the city. In 1455 the mercantry army of Czech obeying the orders of the Prussian governor Jan Bażyński – burnt the city once again in revenge for negotiation canons and Plauen. Only a cathedral, a belfry and a parish church were saved. Soon after that Plauen conquered Frombork, which was – before long – occupied again, this time by the royal marcanry armies.
After the peace treaty in Toruń had been signed, Warmia, still under the control of a bishop, was passed under the management of the Polish Kingdom. The peaceful existence of Warmia was interrupted by the last war between Poland and the Teutonic Order.
In 1520 a canon Nicolaus Copernicus, on behalf of his bishop, was carrying on negotiations with the Grand Master of the Teutonic Knights, Albert von Hohenzolern, whose army was threatening Frombork. The peace lasted for 100 years and then was interrupted by the Swedish Wars. In 1626 the armies of Gustaw Adolf set the fire from the four sides of the city and burnt it completely.
After fortress had been conquered the cathedral and the curia were robbed. All paintings, bells, a marvelous library and jewels fell a prey. The ruined town did not uplift from the fall for the next seven years. It was rebuilt just before the Second Sweden Invasion. The XVIII century and the big fire of the city in 1703, which burnt the whole city apart from the parish church brought more calamities. When Warmia was conquered by the Pruss in 1772 the grounds were taken away from the bishops and canons who were destituted. Soon after that the Napoleonic Wars which took place in this area, destroyed the country with hunger, diseases and contributions. Because of those diseases the city was not able to rise again. From XIX century it was a small settlement living on fishing, without any chance of development.
The city, which used to be an important port by the Vistula Bay, changed into a settlement even worse developed than Tolkmicko placed in the close neighborhood. At the same time, at the beginning of the XIX century Frombork became being famous as place strictly connected with the work, life and death of Nicolaus Copernicus. Because of this Frombork became a popular touristic place, visited by a great number of people.
In 1945 the city was destroyed one more time. Only the cathedral was saved. It was about 60-70% of the city that was destroyed by military operations. Most of the houses were devoided of roofs. The Town Hall, built at the beginning of the XX century, which was not considerably ruined and a lot of houses which were preserved in good conditions, were demolished before 1954. Only seven houses situated in the Old Town and not many more in the area of the Hospital Suburb were left untouched as far as historical buildings are concerned. The gothic parish church, a tower coming from the Middle Ages and the Water Tower were considerably damaged.