Heaven's Gate is a recurring location in the Dept. Heaven series, originating as the first stage in Riviera: The Promised Land. It is an area that links Asgard to the many gates to the surface worlds. Each gate is warded and some of them have a powerful guardian such as Marietta in Yggdra Union to keep surface-dwellers from waltzing into Asgard unbidden.
Heaven's Gate is visited twice. The first time, Ein and Ledah are traveling through it to reach Riviera. Much later, Ein and the sprites travel through it to find and confront Hector, the Traitorous Magus. During the revisit, the area is much darker in tone. This is the first and last stage of Riviera - The Promised Land, and appears in Chapter 1 - Angelic Advent and Chapter 7 - Within The Darkness.
For a detailed guide on Stage 1, click here.
Marietta, the Archangel guards the entrance to Asgard. It is here that the player is presented the option to seal away the Gran Centurio or pick a fight with her and wage war with the gods. If the player chooses the latter in the PSP version and defeats her in battle on a Hard difficulty playthrough, an extra battlefield can be played wherein the Royal Army advances to the Stone Lattice Area that previously appeared in Riviera.