Gniezno is a city in central-western Poland, one of the Piast dynasty's chief cities, it was mentioned in 10th-century sources, possibly including the Dagome Iudex, as the capital of Piast Poland. The Roman Catholic archbishop of Gniezno is the primate of Poland, making it the country's ecclesiastical capital. It has belonged since 1999 to the Greater Poland Voivodeship, and is the administrative seat of Gniezno County (powiat).

There are archaeological traces of human settlement since the late Paleolithic. Early Slavonic settlements on Lech Hill and Maiden Hill are dated to the 8th century. At the beginning of the 10th century this was the site of several places sacred to the Slavic religion. The ducal stronghold was founded just before AD 940 on Lech Hill, and surrounded by some fortified suburbs and open settlements.

​

Legend of Lech, Czech and Rus
According to the Polish version of a legend, "Three brothers, Lech, Czech and Rus, were exploring the wilderness to find a place to settle. Suddenly they saw a hill with an old oak and an eagle on top. Lech said, 'This white eagle I will adopt as an emblem of my people, and around this oak I will build my stronghold, and because of the eagle nest [gniazdo in Polish I will call it Gniezdno [modern: Gniezno].' The other brothers went further on to find a place for their people. Czech went to the South" (to found the Czech Lands) "and Rus went to the East" (to create the Rus' (region)).

​

Cradle of the Polish state
Around AD 940 Gniezno, being an important pagan cult center, became one of the main fortresses of the early Piast rulers, along with aforementioned fortresses at Giecz, Kruszwica, Poznań, Kalisz, Łęczyca, Ostrów Lednicki, Płock, Włocławek, and others. Mieszko I might have moved the capital to Gniezno from Poznań after his own and his realm's baptism, but the actual move may have coincided with a growing German menace in the late 10th century and early 11th century. depositing the remains of Saint Adalbert in a newly built church, to underline Gniezno's importance as the religious centre and capital of Bolesław I Chrobry's kingdom.