Horizon's Reign is both the central spire in Frixion VI's capital city of Mir as well as the first spire ever erected there. Originally meant to be the home for the Tajhan and their throng, over time, it has been repurposed for more political interests; now, it houses the embassies of the Song Dominion affiliates as well as the Welkin Fastness, the monarch's seat of power. As the oldest spire in Mir, the Reign is constantly repaired, restored, and reinforced: the latest update included baryonic titanium plating around its dome (which cost a hefty sum in taxes, much to the chagrin of the citizenry). The spire, and the Fastness more specifically, is also the location of Spire Defense Headquarters, which acts as Mir's police force.
The city is also home to the Luzelio Naberan Memorial Park, a dome which features jagolona vine-woven pagodas, an arboretum of trees donated from various other planets, a paristeel monument dedicated to the park's namesake, as well as a commemorative and immense palladon sculpture garden celebrating the First Interaction.