if not dgn.persist.ziggurat then

  if not dgn.persist.ziggurat or not dgn.persist.ziggurat.depth then

    -- Initialise here to handle ziggurats accessed directly by &P.
    initialise_ziggurat(dgn.persist.ziggurat)

function cleanup_ziggurat()
  return one_way_stair {
    onclimb = function(...)
                dgn.persist.ziggurat = { }
              end
  }
end

local function wall_colour()

function ziggurat_wall_colour()

local function random_floor_colour()
  return wall_colour()
end
function ziggurat_initializer()
  local z = zig()

function initialise_ziggurat(z)

  z.colour = wall_colour()

  z.colour = ziggurat_wall_colour()

end
function ziggurat_initialiser()
  -- First ziggurat will be initialised twice.
  initialise_ziggurat(zig())

local function random_floor_colour()
  return ziggurat_wall_colour()
end

      onclimb = ziggurat_initializer

      onclimb = ziggurat_initialiser

  grid(exit.x, exit.y + 1, "exit_portal_vault")
  grid(exit.x, exit.y - 1, "exit_portal_vault")

  zigstair(exit.x, exit.y + 1, "exit_portal_vault", cleanup_ziggurat())
  zigstair(exit.x, exit.y - 1, "exit_portal_vault", cleanup_ziggurat())