query: #defaultView:Map
  SELECT (?London_Wall as ?id)  
         (sample(?coordinate_location) as ?coord) 
         ?type
         (sample(?instance_of) as ?nature) 
  #       (sample (?London_WallLabel) as ?text)  
  #       (sample(?image) as ?img)
   {
    SERVICE wikibase:label { 
          bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". 
          ?heritage_designation rdfs:label ?heritage_designationLabel. 
          ?London_Wall rdfs:label ?London_WallLabel. 
    }
    ?London_Wall wdt:P361 wd:Q60308.
    OPTIONAL { ?London_Wall wdt:P31 ?instance_of. }
    ?London_Wall wdt:P625 ?coordinate_location. 
    OPTIONAL { ?London_Wall wdt:P1435 ?heritage_designation. }
    OPTIONAL { 
            ?London_Wall wdt:P18 ?image. 
            bind (True as ?AsImg) 
    }
    bind (coalesce(?AsImg, False) as ?type)
  } group by ?London_Wall ?type