When in the early 13th cent. a conflagration destroyed the settlement located on an island formed by the arms of the Narew River joined by the Pełta River, a decision was made to set up a borough and locate it in a place of a more defensive character. The owners, Płock Bishops, indicated for that purpose a piece of land closely bordered by the Narew, where the river and the adjacent swamps made it difficult for potential invaders to advance. It was in so well-chosen a place that a plateau reaching 2-3 meters in height was raised, comprising an area of 60 x 90 meters. Additionally, the place was enclosed by a moat and protected with earthen fortifications from the west and the north. The 1976-85 archaeological excavations enabled reconstruction of the layout of a gradually developing mediaeval borough whose remains were then revealed within the present castle courtyard. The borough was made up of three streets: the east one (about 60 meters long), the north one (almost perpendicular to it), and the so-called central street, running diagonally to the two others. The streets, paved with wooden planks, were lined with one- and two-room houses, each with a hallway. It was presumably by order of Florian Laskary, a Płock Bishop who died in Pułtusk in the year 1333, that the first brick structure was erected on the hill.
The year 1368 saw an invasion of Mazovia by Lithuanian troops headed by Prince Kiejstut. Quite unexpectedly, the troops advanced on Pułtusk and, according to Jan Długosz, a mediaeval chronicler: ". having heaped torchwood round the castle walls, they set the castle, strongly defended[..], on fire, [.] and all the people inside were burnt together with the structure." It was a slow process for Pułtusk to rise from ruin. The Bishops commenced construction of their new abode in the place on the hill denuded by the fire of the borough, and the mediaeval town of Pułtusk spread at the foot of the hill. It was Bishop Paweł Giżycki (1439-1463) who significantly contributed to the development of the Bishops' new castle by turning it into an episcopal residence. He himself stayed in the Small House: a newly erected brick structure designed in rectangle shape, with a cellar, located within today's west wing of the castle. It was not until the 16th cent. that the main Renaissance phase in the development of the castle began. That was when Bishops: Rafał Leszczyński (1523-1527), Andrzej Krzycki (1527-1535) and Andrzej Noskowski (1546-1567) had the so-called Big House (today's north-western wing of the castle) erected, north of the Small House. Their successor, Bishop Piotr Myszkowski, made successful arrangements for surrounding the structure with gardens whose remains can still be seen in today's castle park. In the 17th cent., by order of Bishop Henryk Firlej, a brick bridge leading to the castle was built, with two adjacent turrets, which is still to be seen there. In 1645 Bishop Karol Ferdynand Waza recommended that a gate should be added to it. As results from a description of the site dating from 1650, it was a stately residence, with a dozen or so chambers and two kitchens. There was a polychrome chapel in it, and the library in the basement was Bishop Stanisław Łubieński's legacy bequeathed to posterity. A separate part of the castle was inhabited by a starost entrusted by the resident Bishop with property administration tasks. During the Swedish invasion of Poland, in the years 1655-1657, the castle was taken over by Swedes and damaged severely. It fell prey to Swedish troops again in the year 1703, in the wake of a battle fought by them in the surroundings of Pułtusk with the army of the Elector of Saxony who had ascended the throne of Poland. It was not until the early 18th cent. that the reconstruction of the castle was started, by three Bishops from the Załuski family: Andrzej Chryzostom, Ludwik Bartłomiej, and Andrzej Stanisław Kostka, who had the Big House renovated, and a new (west) wing added to it, closed with a chapel including a sacristy and a treasury. Their coat of arms, Junosza, can still be seen on the outer wall of the west wing. It was also the gatehouse that received an extra wing: a short one, facing the river, with cellars, and with ancillary buildings situated nearby. The castle interiors were decorated with stucco work and paintings, and the walls of the new chapel were faced with Dutch hand-painted faience tiles. The castle gardens received a hothouse provided with a stove heating system, a fig house, and two summer houses.
The 1773 comprehensive inspection of the castle (concurrent with Bishop Michał Jerzy Poniatowski, the King's brother, taking the helm of the Płock Diocese), showed that the castle had been fully restored to operational condition, although certain traces of devastation caused by a powder explosion occasioned by the Russian soldiers stationed there could still be seen. The castle garden could impress many a refined visitor: with its main avenue lined by 85 evergreen shrubs, with its 300 apple trees, more than 150 pear trees, 35 peach trees, and over 100 lemon trees grown in tubs and boxes of various sizes. The castle could also boast its ancillary buildings: its stables with a coach house, a forge, kitchens, and a malt house. The next Bishop of Płock, Hilary Szembek (1787-1795), had the gatehouse rebuilt in accordance with the canons of classicism, with a new wing added to it on the side of the river, intended for the household purposes. During the 1806-1807 military operations the castle was severely damaged. Devastated by soldiers, it was then turned into a hospital. The extent of the damage was such that it prevented Emperor Napoleon I (who arrived in Pułtusk after the historic battle with the Russian army) from staying in the castle, and made him move to a tenement house at the marketplace. The castle served as a military hospital till 1818. It was then that Bishop Adam Prażmowski ordered its renovation. However, as early as 1841 it was seriously damaged by a fire which mainly destroyed its roofs. In the year 1866, after the castle was taken over by the Russian authorities, it was turned into a military hospital again. In the years 1918-1975 the castle housed the Polish poviat administration offices, except for the period of the German occupation when it was used for the administrative purposes by the invader. That was when a new storey was added to its east win
On 27th July, 1974, the Polish Government handed over the former abode of the Płock Bishops, together with the adjacent areas, for the purposes of the Polish communities living abroad, as their Home Place ("Dom Polonii"). The castle, in the shape of a horseshoe, with an internal courtyard, has finally been rebuilt in the Renaissance style, and it inaugurated its first season as "Dom Polonii" (owned by "Wspólnota Polska" Association) in July, 1989. Currently, it houses a quality hotel with restaurants and coffee shops providing a range of ancillary services. This is where numerous conferences, meetings, exhibitions and concerts take place, and the castle is still a mute witness to many a historic event for Pułtusk, Poland and Europe.
Names from the list of famous people staying in the Pułtusk castle: Sigismund III Vasa, King of Poland, Charles XII, King of Sweden, Napoleon I, Emperor of the French, Russian tsars Alexander I and Alexander II.
