A possible dating of the Roman Colonia Ulpia Traiana in Xanten to the years 104 or 105 AD

A possible use of archaeoastronomy is that of dating architectures, in the case that their orientation was determined by some alignments according to sun, moon, or planets and stars. Assuming the Colonia Ulpia Traiana in Xanten, which was built as a new town by Trajan, having the decumanus oriented along a northernmost moonrise direction, we can propose a possible foundation in 104 or 105 AD. To obtain the years we use software CalSKY.