Dun Hallin has an external diameter of around 17.4 metres and an internal diameter of around 10.5 metres.[2] The broch walls currently stand to a maximum height of 3.8 metres on the north and west sides.[2] The entrance is on the southeast side but is in a ruined state.[2] On each side of the entrance passage are oval guard cells, although only the northern, right-hand cell can easily be seen.[2] The interior of the broch has much rubble grassed over.[2] A mural gallery is visible on the southwest side and a lintel stone remains in position over the doorway there. Six steps of the intra-mural stairway were found when the broch was examined in 1921 but are not now apparent.[2]
The broch is additionally defended by an outer stone wall which runs round the edge of the rocky knoll and which is still about 6 metres high to the south.[2]
The broch has not been excavated.[2]
