If you ever visit Ljubljana (of course, if you don’t live here) do visit the cathedral. And look up.
And when you are once there walk around the building. You will be able to find the stones from the Roman graves as well as the copy of the remains (actually it is a copy) of the previous cathedral which stood on that place before 1701.
Actually we can be lucky to have the cathedral as it is, because all sorts of lucky coincidences happened when it was built.