The Levadas of Madeira
Finally on this trip, a quick stop (all the stops were quick, it was a tourist cruise!) in Madeira where I wasn't able to take one of the walking tours of a Levada, famous irrigation channels, but I did manage a photo out of the coach window of one of them .... ('development tourism' perhaps?).
It may look like a concrete pathway but I'm fairly sure - having tried to cross-reference the location with the map below - that is a levada.
Information from the internet: "The “Levadas of Madeira Island” are an hydraulic engineering work ……. defined according to the design and the permanent characteristics of this water transportation system of about 800 km of public and private waterways or aqueducts. The origin of the levadas dates back to the first settlements of Madeira Island, in the first quarter of the 15th century, when water became necessary to water farm lands, particularly sugar cane fields – the first crop of high economic value in Madeira – and for the functioning of the first mills and sugar factories. It is worth noting that in the second half of the 15th century, water carried by levadas was essential to Madeira Island’s becoming one of the largest producers and exporters of sugar in Europe, the “World” of those days." (https://whc.unesco.org/en/tentativelists/6230/#:~:text=The%20Levadas%20are%20channels%20where,houses%20of%20the%20hydroelectric%20plants.)