Walls

Each barrier climbs roughly 50 meters, and all three run as concentric rings around the kingdom's heart. Rails along their tops carry mounted cannons that can be wheeled into firing position against approaching Titans. The material is punishingly hard yet not unbreakable: the Female Titan gouges Wall Sheena while trying to scale it, and the Beast Titan rips chunks from Wall Rose to hurl as projectiles.

Maria forms the outermost ring, with Shiganshina District at its southern edge. Rose sits within it, its perimeter marked by Utopia, Karanes, Trost, and Krolva at the four compass points. Innermost lies Sheena, traditional home of royalty and the nobility, holding the districts of Orvud, Stohess, Ehrmich, and Yarckel along with the capital Mitras and the impoverished Underground beneath it.

Structures of such length could never be watched in full, so the kingdom's defense leaned on the districts, towns jutting outward from each Wall. Titans gravitate toward crowds, and the districts concentrated people deliberately, pulling attacks toward points where soldiers and artillery could mass. Living in one was widely considered the worst lot inside the Walls. The rail cannons above could shell Titans below, though regeneration blunted most of the damage they inflicted.

The Walls' greatest weapon was the secret in their masonry. Millions of Colossus Titans stood hardened within them, and Karl Fritz warned the world that any assault on Paradis would see those giants released to trample everything beyond the sea. Almost nobody inside knew this. The Survey Corps only learned it when the Female Titan's climb cracked Wall Sheena's surface and exposed an enormous face beneath, and Minister Nick of the Wall-worshipping church refused to explain what he knew even when Hange Zoë threatened his life.

Public teaching held that Titans nearly wiped out humanity a hundred and seven years earlier and that the survivors walled themselves into one final refuge. The truth ran differently. Karl Fritz, 145th King of Eldia, chose to abandon the Great Titan War, moved as many Eldians as he could to Paradis Island, and used the Founding Titan to convert masses of his own subjects into the hardened giants that became the three rings, each named for one of Ymir Fritz's daughters. Once Marley began dropping Pure Titans onto the island, the people inside were fed the false history. Fritz also bound his Reiss descendants to a vow renouncing war, privately accepting that if Marley ever chose extermination, Eldia's crimes meant it should be accepted; until then, his people would have their fragile paradise.

In 845 the Colossus and Armored Titans smashed open Shiganshina District, and Wall Maria's entire territory was surrendered. A campaign to retake it sent roughly 250,000 conscripts to their deaths, a scheme that quietly relieved the refugee food crisis. In 850 Trost District was breached but held thanks to Eren Yeager, whose later battle with the Female Titan damaged Wall Sheena at Stohess and revealed the Titans sleeping inside. After the military's coup toppled the Royal Government, Rod Reiss's colossal Titan menaced Orvud District before being destroyed.

The Survey Corps then resealed Shiganshina at the cost of nearly its whole roster, and nine months of culling with the Executioner from Hell cleared Wall Maria for resettlement, after which the Corps reached the ocean. Ties formed with Hizuru and with the Anti-Marleyan Volunteers fed a fifty-year modernization plan sheltered behind the threat of the Rumbling. It never matured. Amid the Yeagerist upheaval, Eren reached Zeke, seized the Founding Titan's full power, and roused the dormant giants; all three Walls crumbled as their Titans marched out.