Which London railway opened in 1890 as the world's first deep-level electric underground railway?

The City and South London Railway opened in 1890 as the world's first deep-level electric underground railway.

The line ran between Stockwell and King William Street, with six stations and a 3.2-mile route beneath London streets and the River Thames. It was officially opened on 4 November 1890 and entered public service on 18 December.

The railway was originally intended to use cable haulage, but the cable contractor went bankrupt during construction. The promoters switched to electric locomotives, powered by a third rail, making the railway a landmark in electric traction. Its narrow tunnels required unusually small carriages, soon nicknamed “padded cells.”

The District and Metropolitan railways were older, but they were shallow, cut-and-cover systems that initially used steam locomotives. The City and South London Railway was later extended and ultimately became part of today’s Northern line. Its pioneering tunnels and alignment remain part of London’s Underground network.