text: First of all a preliminary remark: The search result of Google should not be in the first place in this consideration ;-)
  Let’s have a look at the possibilities:
  - “Wachturm am Reckberg” (Watchtower on Reckberg): It doesn't reveal what kind of watchtower it is. Is it still in operation? The information "Reckberg" is superfluous, since the geographical location is determined by surrounding objects.
  - “Römischer Wachturm” (Roman watchtower): At least this name shows the period and the “design”.
  What do you suggest?
  In another map I once saw "Limestower Reconstruction". That would be the most appropriate. I don't regard the unambiguity as a severe criterion. That would also be difficult; where should the official name come from? It is also not a monument with an official registration. Have you ever looked for "Obertor"? There is one in Neuss, but also elsewhere.
  One possibility would be "Wachturm am Reckberg (Neuss)" as alt_name.