Macragge

Macragge is an Imperial Civilized World located in the southern reaches of the Eastern Fringe of the galaxy in the Ultima Segmentum. It is also the Chapter homeworld of the Ultramarines Chapter of Space Marines and the capital of the Ultramarines' Realm of Ultramar. Macragge itself is mostly bleak and rocky, with more than three-quarters of its land mass formed from mountainous upland almost entirely devoid of life. The people of Macragge do not live in this inhospitable region, but the fortress-monastery of the Ultramarines, the Fortress of Hera, is built here upon a craggy peak surrounded by impenetrable mountains.

Since the 13th Black Crusade was unleashed against the Imperium, Macragge has been the site of three major military engagements fought between the Ultramarines and the enemies of the Imperium. It was here that the Primarch Roboute Gulliman was reborn and with a terrible wrath, he would lead the Indomitus Crusade alongside the Ultramarines.

Reference

 * Picture Reference
 * Warhammer 40k Macragge