> [...] Madrid has a dense network too (≈0.50), though well behind Paris.
As a native of Madrid, I must point out that using the nominal surface area of the municipality of Madrid (~605 km²) is misleading for these purposes due to the Monte del Pardo [0] and Soto de Viñuelas [1], two fenced off forest areas covering around 180 km² between them. The impact of these areas on the nominal surface area of the city is visually obvious when you compare the outlines of Madrid and Paris administrative areas:
As a result, the relevant surface for estimating the density of Metro stations in Madrid should be at most ~425 km². While one may arguably also want to exclude the Bois de Boulogne and the Bois de Vincennes from the surface area of Paris, even the "de-Pardo'd" surface area of Madrid still contains significant non-urban areas such as the Casa de Campo forest, large non-built-up areas, and even most of its airport.
(In any case though, after this pedantic "well ackshually", I must also point out that a few Madrid Metro stations actually fall outside of its municipal limits. I would get out more, but I live in a town without a Metro)
> [...] Madrid has a dense network too (≈0.50), though well behind Paris.
As a native of Madrid, I must point out that using the nominal surface area of the municipality of Madrid (~605 km²) is misleading for these purposes due to the Monte del Pardo [0] and Soto de Viñuelas [1], two fenced off forest areas covering around 180 km² between them. The impact of these areas on the nominal surface area of the city is visually obvious when you compare the outlines of Madrid and Paris administrative areas:
+ Madrid: https://www.openstreetmap.org/relation/5326784
+ Paris: https://www.openstreetmap.org/relation/7444
As a result, the relevant surface for estimating the density of Metro stations in Madrid should be at most ~425 km². While one may arguably also want to exclude the Bois de Boulogne and the Bois de Vincennes from the surface area of Paris, even the "de-Pardo'd" surface area of Madrid still contains significant non-urban areas such as the Casa de Campo forest, large non-built-up areas, and even most of its airport.
(In any case though, after this pedantic "well ackshually", I must also point out that a few Madrid Metro stations actually fall outside of its municipal limits. I would get out more, but I live in a town without a Metro)
[0] https://en.wikipedia.org/wiki/Monte_de_El_Pardo
[1] https://en.wikipedia.org/wiki/Soto_de_Viñuelas