🇷🇺 Russia · Ancient city
Derbent — Naryn-Kala Citadel and Double Walls (Caspian Gates)
Caucasian Albania to Sasanian to Islamic (c.100 BCE–19th c.; peak Sasanian 6th c.) · Caucasian Albanian → Sasanian Persian → Khazar → Arab → Shirvanshah → Russian
Sasanian 3.6 km double-wall Caspian Gates with Naryn-Kala citadel sealing Caucasus passage.