The Gate of Darkness was excavated in 1824, at the same time as the Esztergom Church. It is a long tunnel located under the artificial slopes of the castle hill and connecting the seminary and the church houses. It is 90 meters long and follows the line of the former eastern walls of the castle, and is characterized by its neoclassical style It includes a barrel vault, was completely renovated in 2006 and, contrary to its name, is today lit by incandescent lamps, attracting many visitors to walk through it.