The Mariendom is the defining landmark of Linz and Austria’s largest church. Built between 1862 and 1924, the Neo-Gothic cathedral dominates the city skyline. Responding to social change and the declining significance of religious institutions, the Diocese of Linz added the new Domcenter on the cathedral’s eastern side. The extension opens the church toward the city and creates a link between sacred space and urban life. As a new entrance, the Domcenter welcomes visitors with a café and information desk. A redesigned sequence of spaces leads through the former sacristy and the East Tower Chapel into the historic tower hall. The chapel displays the cathedral treasury alongside interactive exhibits, while an integrated elevator offers new views of the stained-glass windows. Architecturally, the Domcenter combines historical references with a contemporary design language. Three canopy-like exposed concrete vaults reinterpret Gothic forms through their inverted geometry, creating a light, floating appearance. For conservation reasons, the extension is structurally detached from the cathedral. The load-bearing concrete shell shapes the interior atmosphere, while the insulated upper shell meets functional requirements. Inside, a linear counter guides visitors through the building. The Domcenter combines cultural, tourist, and pastoral functions while accommodating diverse events. The project revitalizes Cathedral Square and establishes a new destination in the heart of Linz.