Eighth Door

The Eighth Door was, like the seventh, a matrix door that allowed one to physically enter the micro-universe of the Matrix.

While wandering the Doctor's TARDIS, Ace found the Eighth Door. Inside the dove-grey wall of roundels faded away into a rosy sunrise sky, the sun never seeming to set, while a wide expanse beach with calm, cold, white water lapping at its pebbled edge stretched into infinity. (PROSE: St Anthony's Fire)

The Eighth Door onboard the Time Station allowed Romana II to enter the Matrix and encounter Rassilon. (AUDIO: Neverland)