John from Lajsy is a “founding father “ of Olsztyn. He transformed the Allenstein watchtower, situated in a bend of the Łyna River, into a town of the same name. On 31 October 1353, he received a charter of incorporation issued by the cathedral chapter.

On the basis of this privilege he was appointed founder of Olsztyn and received the hereditary title of village administrator (later called the mayor). He was born in 1310 in Łajsy near Pieniężno and came from a family that rendered outstanding services in the field of the colonization and development of Warmia. His grandfather Martin founded, among other things, Łajsy whose later administrator was John’s father Geriko, whilst the latter's brother Henry was the administrator of the villages Barczewo and Skajboty. John made good use of the organisational skills he had learned at home. He created the very layout of the streets of the central square in the Old Town as well as the defensive walls with the High Gate, which is preserved to this day. John from Lajsy also founded Praslity and Różnowo, but just the city by the Łyna River achieved the greatest success. Thanks to this, John became a nobleman (1372) and went into the annals of history. Today, the commemorative plaque with his image hangs under the arcades of the Old Town house (called “burmistrzówka”). The present building stands on the foundations of the first brick tenement house in Olsztyn, which was built by John. Today, John still overlooks Olsztyn’s authorities from his portrait, which hangs in the town hall meeting room.

The shortest street in Olsztyn’s Old Town, measuring only 43m, was named after John. He also ended up on the banknotes issued in Olsztyn during the crisis in 1921. This money was called “povertymoney” (“biedapieniądze”).