The Greenwich Foot Tunnel is a pedestrian tunnel that runs under the River Thames in London, connecting Greenwich on the south bank with Millwall on the north. It was opened in 1902 and designed by civil engineer Sir Alexander Binnie. The tunnel is about 1,215 feet long and features lifts and helical staircases for access. Despite some upgrades over the years, like new lifts and CCTV, the tunnel has faced occasional closures and delays. Around 4,000 people use it daily, but cyclists must dismount and push their bikes through.