I am currently inside a tunnel with a 70 km/h speed limit sign, which suggests a European or international metric system. The road markings are white dashed lines, and the tunnel walls are tiled with a distinct horizontal band. The lighting and overall infrastructure design feel very characteristic of modern European tunnel engineering. I suspect this is in a major city in a country like Spain or France. I am moderately sure of this region.

then: forward

The tunnel environment remains consistent with high-standard European infrastructure. The specific tile pattern and lighting arrangement are very reminiscent of the tunnels found in major urban centers like Madrid, Spain. Given the lack of external visual cues, I am relying on the architectural style of the tunnel interior. I am fairly confident this is in Madrid, Spain.

then: guess