The Arnos Park Viaduct is a railway viaduct of 34 brick arches that was built as part of the extension of London Underground's Piccadilly line from Finsbury Park in the south to Cockfosters in the north. It was built in 1932 and opened in 1933. It starts on the southern edge of Arnos Park soon after Arnos Grove station and ends on the northern side of the park, where the line enters a tunnel that continues to Southgate.