Brzeg, situated halfway between Wroclaw and Opole, is one of the oldest and most beautiful towns in Silesia. The first mention concerning the formerly existing fishing and merchant settlement of Wissoke Brzegh comes from 1234. The location at the junction of overland and water routes connecting the largest centres of medieval Silesia with the neighbouring countries facilitated the town’s establishment. The establishment of Brzeg came by virtue of the Western European foundation law issued between 1246 and 1248 and confirmed in 1250.
The foundation document issued by the Wroclaw duke Henry III determined the foundation area, which is visible in the old town housing development even today. The congregations and monasteries (Franciscans, Dominicans, Antonis and Knights of St John of Jerusalem), settled in the town at the turn of the 13th and 14th centuries.

These congregations erected their churches and monasteries. After the division of the Wroclaw Duchy in 1311, Brzeg became the capital of the smallest among the three newly created duchies, i.e. the duchies of Wroclaw, Legnica and Brzeg.
The period of the Brzeg’s prosperity is inseparably bound up with the reign of the Piasts (the first Polish royal dynasty) in the Legnica and Brzeg duchy. Duke Boleslaw III, son of the Wroclaw duke Henry V was the first one to join the Brzeg duchy to the Legnica duchy and use „The Ruler of Legnica and Brzeg” title in 1312. Both duchies were later joined and separated on several occasions. In 1329, Boleslaw III became the Czech feudl collector and in 1342 made Brzeg his own residence. In the second half of the 14th century, the most important patron in the fields of construction and culture was duke Ludwik I. The duke extended the castle, next to which he established Saint Jadwiga’s collegiate church with a rich book collection. The most valuable item of the book collection was the illuminated legend of Saint Jadwiga (the so-called Lubin Code). Duke Ludwik I financially supported the reconstruction of St Nicholas’ church. After the fire in 1380, the town hall was reconstructed too.

In 1390, duke Ludwik I carried out the first archaeological research recorded in Poland in a former castellan’s fortified settlement of Ryczyn near Brzeg. Between 1428 and 1432, Brzeg was destroyed by the Hussites. Numerous natural disasters descended upon the town on several occasions. In 1443 for instance, the vaults of the St Nicholas’ church collapsed during an earthquake.
During the period of the biggest territorial growth, the Brzeg Duchy included Lubin, Chojnow, Olawa, Kluczbork, Byczyna, Wolczyn as well as Niemcza and Strzelin (after 1427).

Since the middle of the 15th century, its territory was gradually decreasing. In the second half of the 15th century, the town went through an economic decline. In the 16th century, during the reign of Jerzy I, Brzeg regained its lost title of the capital of the Legnica and Brzeg duchy. The heyday of its architectural and cultural growth was brought by the reign of his successors Fryderyk II and Jerzy II. Duke Fryderyk introduced Lutheranism to the town and the duchy. Franciscans and Dominicans left the town during his reign. Fryderyk II started the Renaissance conversion of the castle. Due to the threat of the Turkish invasion, the duke decided to reconstruct the municipal fortifications. During the fortification works, the oldest church (known from the historical sources), the Romanesque Holy Virgin Mary’s church was demolished. In 1545, the Dominican church and monastery were pulled down as well. Jerzy II continued the construction works. His greatest achievement was the reconstruction of the castle based on the Renaissance architecture, which was carried out by Italian architects. It was also them who thoroughly rebuilt the town hall after the fire in 1569. The duke supported culture and science, and founded the Illustre Bregenese High School later called the Piast Gymnasium.
After 1582, the Franciscan church was converted into an arsenal. In the 16th century, Brzeg was a resilient commercial centre. It was here that cattle from the borderlands of Poland was brought to the famous fair and sold to merchants coming from all over Germany. During the Thirty Years’ War, Brzeg wasn’t conquered by the Swedish army besieging it thanks to its fortifications extended in the 16th century. The war however, had a negative impact on the duchy and the town. In 1675, the last male representative of the Piast dynasty – Jezry IV Wilhelm died. After this event, the town and the duchy was incorporated into the Hapsburg monarchy. The Hapsburg rules brought attempts of the Catholic religion reintroduction. In place of the removed monasteries and congregations in the 16th century Jesuits and Capuchins were brought and they erected their monasteries and churches in Brzeg.

In 1741, Brzeg was severely destroyed during a siege by the army of the Prussian king Frederick II the Great. A year later, it fell into the Prussian hands together with the whole region of Silesia. Brzeg became a county town with a military garrison. The first river lock on the River Odra was constructed in 1748 and the fortifications were extended as well. After the occupation by Napoleon’s army in 1807, the existing fortifications were pulled down and replaced by promenades and parks. The railway service reached the town as early as in 1842. In the middle of the 19th century, Brzeg declined and became a municipal centre of a local importance. This situation continued till the 1870’s. The turn of the 19th and 20th centuries was the time of the town’s development. In 1907, Brzeg was separated from the county and received the higher rank of an independent town. In the 1920’s the economical situation of the town was deteriorating until a military garrison was once again located here and the town could take advantage of the airfield built in 1916. The World War II brought the most severe destruction in the whole history of the town as well as the national status change. The reconstruction works after the war were accompanied by industry development – mainly food processing and electric machinery industries. New residential districts were established in the developing southern part of the town.
Until 1950, Brzeg was located in the Wroclaw Province and after the administrative reform, it was incorporated into the Opole Province. During the millennium celebrations of the Baptism of Poland, there were the so-called „the developments in Brzeg”. In May 1966, the police removed clergymen from the parish house located at the Castle Square despite the objections raised by the residents. These objections triggered the repressive measures of the secret police. After the administrative reform in 1975 the Brzeg County was liquidated. In 1997 the northern part of the town suffered from the flooding, which afflicted southern Poland. Since January 1999, Brzeg has been the capital of the county once again.