The city lies on the Kopanica River (a right tributary of the Barycz), 9 km south-east of Leszno. The baroque urban layout, unparalleled in Poland and rare in Europe, has survived. Built in 1738-1762 at the behest of Aleksander Józef Sułkowski, it was designed by the renowned architect Karl Martin Franz. The open space composition was based on an system of axial and radial streets that would join the city centre with the spacious lordly manor.
Rydzyna was first mentioned in 1403 as the property of Jan of Czernina of the Wierzbno coat of arms. Jan was from a wealthy family and moved the family seat here from Silesia. Over time, the family adopted the name Rydzyński from their estate.
The founding of the city in 1407 was confirmed in 1551. A lot of Hussites came here from Bohemia during the 15th century. This was a vibrant crafts centre in the 16th century. Rydzyna passed to the Leszczyński family at the end of the 18th century and was the Sułkowski family seat from 1738 to 1909.
There was a secondary school run by the Piarist Fathers here from 1774 to 1820 and, from 1784, an Academy of Knights. The castle housed an elite secondary school from 1928 to 1939. It was renowned for its high standards and modern teaching methods.
The central point is the small square marketplace with its vertical and peak-roofed baroque and neo-baroque tenement buildings dating from the 18th and 19th centuries. The Holy Trinity monument in the middle of the marketplace dates from 1760–1761 and recalls an epidemic of plague in 1709. The baroque town hall from 1752, with its wooden cupola, stands on the western edge of the marketplace.
The baroque St. Stanislaus Church, designed by K. M. Frantz and built in 1746–1751, is north-east of the marketplace. The Gothic marble tombstone of the city’s founder Jan of Czernina from 1422 is behind the high altar. This is one of the oldest knightly tombstones in Wielkopolska.
A late-baroque, formerly Evangelical church (built in 1779-1783) and “Józef”, a reconstructed wooden post mill that now houses the Museum of Milling and Agriculture, can be found on the way to Leszno.
A 15th-century castle, formerly the residence of the local lord, adjoins this circular city from the east. The baroque Leszczyński residence, designed by Józef Szymon Belotti, was built partly within its walls in 1682-1695. An baroque-classicist construction from the 18th century stands opposite the castle. A group of monumental trees, including a plane tree with a circumference of 550 cm, stand out front. On the east side of the castle is a 6.9 ha park, originally regularly laid out, from the late 17th century. This was turned into a landscape park with a stately stand of trees c. 1820.