Complex sentence: In the 18th century, the building in Barndesteeg alley was used as a clandestine church ("schuilkerk") by the Old Catholic parish, which purchased the building in 1705 and dedicated it to the saints Peter and Paul.
Split into simpler sentences: In the 18th century, the building in Barndesteeg alley was used as a clandestine church ("schuilkerk "). The Old Catholic parish purchased the building in 1705 to use as a"schuilkerk" devoted to the saints Peter and Paul.