Ad Pirum

Is it worth the trip?

Yes, if the late Roman frontier interests you or you are driving between Ljubljana and Ajdovščina anyway: this is the main fort of what the museum calls the largest Roman-era monument in Slovenia, it is free, and you can walk it whenever you like. Be clear about what you will see. Nothing stands to its full height, and the towers and gates survive as footings, so the pleasure is in tracing a big fort on the ground in forest and meadow, not in looking up at walls.

Getting there

Hrušica is on the old road between Logatec and Ajdovščina. The museum gives the routes from Ljubljana via Logatec, Kalce and Podkraj, and from Ajdovščina via Col; both roads are cleared of snow in winter. You park at the Stara pošta inn, and the museum recommends walking boots. No bus stop is mapped nearby, so plan on a car.

The park is open at any time and costs nothing. The museum room in the inn opens Wednesday to Sunday — 11.00 to 19.00 midweek, from 10.00 on Saturday and from 09.00 on Sunday — and is also free. Guided tours for groups can be booked from April to October (National Museum of Slovenia, read 26 September 2026).

Two more Claustra forts are close by: Lanišče, 6 km by road towards Logatec, and Castra in the centre of Ajdovščina, 13 km the other way (the museum).

History

Before there was a fort, the Romans built a post and relay station here, together with the state road of the Augustan period. The new road from Aquileia to Emona through Ajdovščina and over Hrušica replaced a longer route and saved a day’s travel between the two towns; from the 2nd century a beneficiarius post, a kind of police station, stood here as well (National Museum of Slovenia).

The fort came when raids across the frontier shook the long peace. Published dates differ: the museum puts it in the late 3rd century, while the English Wikipedia article, citing Peter Kos (2014), says the 320s. Either way it belonged to the Claustra Alpium Iuliarum, more than 80 km of walls, towers and forts begun in the second half of the 3rd century and fully in operation in the Constantinian period, the first half of the 4th century. Around 500 soldiers — a cohort — could be quartered here, and the road ran straight through the fort between two gates with towers probably 10 m high (the museum).

The fort was abandoned in the 5th century, though traffic on the road continued until at least the end of the 6th. Between the 12th and 14th centuries a church of St Gertrude, patron of travellers, was built inside the ruins, and a regular post service between Gorizia and Ljubljana used the old road until the middle of the 19th century; the building of today’s inn was its post station (National Museum of Slovenia).