The London and Greenwich Railway (L&GR) was opened in London between 1836 and 1838. It was the first steam railway in the capital, the first to be built specifically for passengers, and the first entirely elevated railway.

An elevated railway or elevated train is a railway with the tracks above street level on a viaduct or other elevated structure. The railway may be broad-gauge, standard-gauge or narrow-gauge railway, light rail, monorail, or a suspension railway. Elevated railways are normally found in urban areas where there would otherwise be multiple level crossings. Usually, the tracks of elevated railways that run on steel viaducts can be seen from street level.