Complex sentence: Notably, lines B, C, and D share a station under the Obelisk, which is the focal point of the subway system and has the only underpass below the avenue, featuring a commercial gallery.
Split into simpler sentences: Notably, lines B, C, and D share a station under the Obelisk, which is the focal point of the subway system. This station also features the only underpass below the avenue, featuring a commercial gallery.