Castledykes near Carstairs was one of the substantial Roman bases of Clydesdale. Successive occupations left rebuilt defences and a wider landscape of enclosures and camps, showing the importance of this route through southern Scotland.
Visit Castledykes
📍 Location: Corbiehall, near Carstairs and Lanark, South Lanarkshire. Grid reference NS 929 443.
👁 What survives: Surviving portions of earthwork defences and extensive buried archaeology.
⭐ Best for: Understanding a substantial fort on the routes through Clydesdale.
🥾 Visit: The fort lies in agricultural land. Follow existing access routes and respect farm operations.
🏛 Nearby Roman places: Crawford to the south and Bothwellhaugh farther down the Clyde.
Castledykes at a glance
| Feature | Evidence and interpretation |
|---|---|
| Occupation | Flavian occupation from around AD 80, followed by Antonine reoccupation in the AD 140s–160s, with changes and interruptions. |
| Garrison | Unidentified main garrison. A lead seal connects the site with ala Sebosiana, without proving that the whole regiment was stationed here. |
| Size | Approximately 174 × 160 m internally: 2.78 hectares (6.88 acres). |
| Probable troop strength | About 1,000 troops is a working Antonine estimate; actual strength and composition remain uncertain. |
A fort used more than once
The site saw late-first-century occupation and a return during the Antonine advance. The defences changed, including enlargement of the turf rampart. The Antonine sequence itself was not necessarily uninterrupted: evidence for withdrawal and renewed occupation cautions against imagining one unit living here continuously from the AD 80s to the 160s.
A base for around a thousand?
The supplied dimensions produce an estimate close to 1,000, and Hodgson’s model of the Antonine deployment uses the same broad figure. This agreement provides a useful scale, but not proof of a thousand-man cohort. Roman unit titles were not literal attendance registers, and space could be shared by detachments or used for horses and storage.
A cavalry connection
The supplied Antonine Wall volume notes a lead seal of ala I Gallorum Sebosiana at Castledykes. A seal is evidence of a connection: personnel, supplies or correspondence could move between forts. It is not sufficient on its own to place the regiment’s entire establishment here. The unit link is therefore a possibility to explore, not a settled garrison list.
Inscriptions and the identity of the troops
A separate inscribed object, Britannia 30.22, is a copper-alloy die found near the fort in 1998. Its letters are interpreted as abbreviated personal names. It is not the ala Sebosiana lead seal and does not identify the garrison. Keeping these objects distinct avoids turning a personal mark into a unit inscription.
For the regiments and types of troops represented across Scotland, see Auxiliary units in Roman Scotland. The Roman Army guide explains the wider organisation, while Roman fort layout introduces the buildings found in permanent bases.
References and further reading
- Historic Environment Scotland: Castledykes, NRHE 47721 — site record, archaeological notes and excavation bibliography.
- RIB Online: Britannia 30.22, copper-alloy die
- Ala I Gallorum Sebosiana: unit history
- Nick Hodgson (2020), ‘Why was the Antonine Wall made of turf rather than stone?’, in The Antonine Wall: Papers in honour of Professor Lawrence Keppie, Appendix 1, p. 309; unit discussion p. 311 — hypothetical deployment model, consulted in the supplied volume.
- Roman Inscriptions of Britain: search Castledykes — consult find contexts and commentary; a search result is not itself evidence for a garrison.
- Romans in Scotland fort-size spreadsheet — supplied copy used for dimensions and rounded capacity estimates, with archaeological measurements preferred where revised.
- Paul Holder (2003), ‘Auxiliary Deployment in the Reign of Hadrian’, especially p. 120 — nominal unit organisation, consulted in the supplied PDF; not a local garrison identification.
