Anchor telephone exchange
Anchor Exchange is an underground telephone switching system and former hardened telephone exchange built in Birmingham, England.
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).
Other tunnels in United Kingdom
Delaware Aqueduct United States · 137 km Päijänne Water Tunnel Finland · 120 km Orange–Fish River Tunnel South Africa · 82.8 km Ishikawa Tunnel Japan · 78.5 km Brenner Base Tunnel Austria · 64 km Mont d'Ambin base tunnel France · 57.5 km Gotthard Base Tunnel Switzerland · 57.09 km Hong Kong–Zhuhai–Macau Bridge China · 55 km