Hi @ErmesT
“However it surprise me that you see the blue lines, as the blue lines are normally associated to an existing Road or pathway. In fact, to be able to add some street view I had to add the pathways first.”
There are actually two kinds of Google Street View coverage:
- regular coverage, usually taken by cars: this needs a road on the map to appear (it can be a green dashed line as well for footpaths) and makes 99% of Google Street View
- off-road coverage, also named trekker coverage as it is often made using the Trekker (backpack with camera): this one can exist without any road on the map because it often features off road view which by definition do not have road on the map. Includes trails, interior views (museums…), boat views and more.
Most of parks will have off-road coverage and can exist without needing to be mapped and this one is a good example. Sometimes Google will use this feature for countries that have very bad maps or just no roads at all, like Mongolia where the Google car drove the steppes far from any actual road, or the Faroe Islands where the map data is incorrectly placed. Without this the coverage couldn’t appear of Maps.
As for this park in Portugal, I did visit it a few years ago and the only access is through the building so there is no public access from a regular road as far as I know.