The architecture repository acts as a holding area for all architecture-related projects within the enterprise.

The repository allows projects to manage their deliverables, locate re-usable assets, and publish outputs to stakeholders and other interested parties.

Source: TOGAF 9.1 Chapter 36.2.5.

If the enterprise uses a tool for modelling its architecture, then also the contents of the tool, such as the model elements and the views are part of the architecture repository.

Alongside the breadcrumbs for this item which shows its "ancestry" in concept space, the Child items tab lists its descendants, and the Siblings items tab the concepts that exist under the item's "parent item".