He brought to Opole the relics of probably the Holy Cross from the Holy Land. The symbol of this venture, as historians claim, is the cross next to the Piast eagle in the coat of arms of Opole. But it is not everything! On the way back from the crusade in 1218, Casimir I stopped in the Balkans. From there, he brought to Opole his wife, beautiful Bulgarian girl - Viola. Their wedding took place probably in 1220. Kazimierz was 40 years old, and Viola 15. Such age difference did not impress anyone in the old days.  He has founded the city in 1217, and in the following years he established here a place for the authorities, administrations and church hierarchs. Under Casimir I, it was decided to build a now-defunct castle in Ostrówek, and in the same time the walls surrounding the city were being built. He died in 1230. His monument was unveiled in Opole in May 2018, as part of a celebration of the 800th anniversary of the city. It was placed in the center, near the Opole Town Hall, almost in front of the Franciscan church, where the Piast dukes were buried, near the Opole Cathedral. The bronze sculpture made by the artist from Opole Wit Pichurski weighs nearly 2 tons. A time capsule has been buried next to it with wishes and messages for the future generations.