I came across some extraordinary posts about the fragments of Jewish life in Poznan, written by Erik Ross, a priest of the Dominican order, whose blog appears in the Times of Israel.
His posts are heart-wrenching and entertaining, full of photos, personal reflections, and difficult facts.
In Walk down Jew Street, he describes the frescoes in the Church of the Holy Blood of the Lord Jesus (Kościół Najświętszej Krwi Pana Jezusa). The church is on what is now called “Jewish Street” but inside, the recently renovated paintings depict the story of the desecration of the host by three Jews. Most striking to me, Ross points out the many places around town where this story is renewed–in the weekly opportunities to get miraculous water from the well below the church (where according to legend the Jews tried to wash off the blood that ran from the stolen hosts where they had stabbed them); in the fresh gold leaf on the Latin words recounting the story in the Corpus Christi Church, as well as three newly painted doll-sized figures of Jews around a well under a fragment of alter (marking the site where the stolen hosts were discarded in what was originally a swamp, reclaimed by a priest who brought them to another church, but then miraculously flew back to the swamp leading to the decision to build the church there).
But you should read his post, which goes into much more detail.
Ross has also written Fake Lake, about the beautiful Lake Rusałka that was built with Jewish slave labor and reinforced with Jewish tombstones, and Swim-a-gogue about the pool that until recently filled the main sanctuary of the synagogue (I’ve written about it too, in Swimming in the Synagogue).