Researchers have always presumed that Ansgar's church must have been located within the Hammaburg fortification. When four particularly thick, squared timber posts that were exactly in line with the later Gothic cathedral had been discovered during the first excavations in 1949, they were immediately interpreted as coming from Hamburg's ancient church. It is now clear, however, that the remains of the posts are significantly younger and belong to a wooden church, which was probably built by Archbishop Unwan in the 1020s. This so called "Unwan Cathedral" today is the oldest documented church building in the cathedral square. It was first built on the abandoned castle grounds after the demolition of Hammaburg III. So far, Ansgar's church cannot be found. There is evidence to suggest that its remains lie under the St. Peter's Church just north of the former Hammaburg.