This archive tracks four layers. A record present in 4 of them (HH, AoI, M41, IND) is silent in the rest, and says so.
The Horus HeresyM30–M31
imperium
Capital of Ultramar; seat of Imperium Secundus
Guilliman's adopted world and the administrative centre of the Five Hundred Worlds. With Terra unreachable behind the Ruinstorm, a second Imperium was proclaimed from here.
Age of the ImperiumM32–M40
imperium
Capital of Ultramar
Chapter homeworld of the Ultramarines and the one world besides Terra and Mars permitted dominion over other worlds.
The 41st Millenniumpre-Rift
imperium
Capital of Ultramar
A cold, mountainous, heavily fortified world running the most orderly stretch of the Imperium. Hive Fleet Behemoth was stopped in its orbit at ruinous cost.
Era Indomituspost-Rift
imperiumImperium Sanctus
Capital of Ultramar; Guilliman restored
Guilliman was brought back to life here at the close of the 13th Black Crusade, and the Indomitus Crusade's eastern effort has run out of Macragge ever since.
Position
Map frame: 696, 566 in the archive's 0–1000 disk space (core at 500, 500).
Distance from the core: 207 units ≈ 22k light years, east of the galactic core.
Height above the disk plane: -5.2 units — invented thin-disk jitter, deterministic per record. No published source gives any location a z coordinate.
System: Macragge System
Books set here
22 titles in the reading tracker touch this record, 9 of them as a primary location. Titles link out to the tracker.
wh40k.lexicanum.com/wiki/Macragge infobox Class = Adeptus Astartes Homeworld, which is NOT a terrain type. The page carries its own "Conflicting sources" note: older material gives "a dust ocean that covers 4/5ths of the planet's surface", newer gives watery oceans and ice storms, and it states plainly "Macragge's climate is temperate". RENDERED temperate from 2026-09-01 (Bobby's call): the old fortress render was chosen because the world HOSTS a fortress-monastery, not because the planet looks armoured
gposmedium
derived: Ultima Segmentum, 'located to the east of Holy Terra' (Lexicanum:Ultima_Segmentum), and Ultramar borders the Eastern Fringe. Placed far east but still just inside the Astronomican's ~50,000 ly reach from Terra, which is what makes Ultramar the last well-lit realm before the dark