Route 20 (Koshu Kaido) Corridor, Yotsuya-Sanchome, Tokyo

Route 20 carries the old Koshu Kaido through Yotsuya-Sanchome, a district in Tokyo's Shinjuku Ward. The road began as one of the five great highways of the Edo period, linking the shogunal capital to Kofu in Yamanashi Prefecture, and it now runs as National Route 20 through the heart of the city. Yotsuya-Sanchome sits at a junction served by Tokyo Metro's Marunouchi and Shinjuku lines, connecting commuters to Shinjuku Station a few stops to the west. The corridor is lined with multi-story commercial buildings whose upper floors carry stacked signage for retailers, clinics, and offices, a common building pattern along Tokyo's older arterial roads. Traffic along this stretch links Shinjuku to the Yotsuya and Ichigaya districts further east.