Searchable items

Forgive the newbie question here…

How do you make an item that is searchable but does not sit on the map all of the time?

An example of what I am talking about is the Derwent Valley Aqueduct as shown here:
https://www.openstreetmap.org/way/203937958

When you just look at the general map it does not show, however when you search out this actual ‘way’ you can view it on the map.

How do you add an item like this?

It’s pretty simple - some objects, like pipelines for example, are not rendered on one on more map layers, but all data on the map can be seen by using “?” icon on the OSM.org site.

… and somewhere there’s usually a map layer that shows whatever it is you’re adding! This bit of the Derwent Aqueduct, for example, can be seen at https://map.atownsend.org.uk/maps/map/map.html#zoom=15&lat=52.84608&lon=-1.29382 .