Structure AC — the small round building

Structure AC is described by Karul in 2021 as a small round building, about 5.5 metres across, standing roughly 20 metres north-east of the AA / AB / AD cluster. It is a hybrid in construction: its southern half was carved out of the living bedrock, while its northern half was formed by vertical standing stones — a mix of the 'cut-down' and 'built-up' techniques that both appear at Karahan Tepe.

At the end of its use AC was covered with large flat stones, a capping limited to the area of the structure itself — Karul notes the stones did not overflow beyond the building's boundary, and the room's inner fill was still unexcavated at the time of his report. That deliberate sealing echoes the treatment of the neighbouring buildings, where rooms were filled and closed rather than left open.

AC is interesting precisely because it is small and mixed. Karahan Tepe is celebrated for rooms carved down into bedrock, but AC shows the builders combining that subtractive approach with ordinary walling of upright stones in a single structure. The result is a compact building that sits, technically, between the rock-cut chambers and the free-standing masonry buildings elsewhere on the site.

Its position a short distance from the central cluster also matters: AC is close enough to belong to the same group as AA, AB and AD, without being part of the monumental core.

AC belongs to the early round-plan phase — the same stage as AD, AB and BF — and its deliberate capping is a small instance of the practice Karul's 2025 report makes central: at Karahan, rooms were filled and closed on purpose rather than left to decay, so the mound itself came to hold a memory of what had stood there.

Beyond the plan, scale and covering, little about AC is settled. Karul's description does not resolve the building's internal fill, its precise phase, or its function, and the exact relationship between AC and the larger central buildings has not been published in detail. This is an active excavation, begun in 2019 and still thinly published, so AC is best read as a securely described building whose story is not yet fully told.

What can be stated plainly: a small round building, part rock-cut and part built of standing stones, capped with flat slabs, near the central group. Everything past that is a lead for future work rather than an established conclusion.