One Fort - One Unit

[MARCvSVIBIvSMAvRINvS]

Marcus'
This is backed up by the point that only one Headquarters building is ever found (as Dr Campbell's point later). I would also not be surprised if things like roof tiles were not made in bulk elsewhere and shipped in; that said, they could be marked for the maker, or potentially for the destination!

Lastly, yes, the 'one headquarters building' is a very good argument. From my side, however, I would argue that a single headquarters building in a legionary fortress is enough to manage 10 cohors, so why couldn't a similar one in an auxiliary fort cope with 2-4 units. In addition, there could be separate smaller Tribune/Prefect houses with even a shared 'praetorium' facility to be found. However, not surprisingly, I will jump at the example of your Auxiliary Forts booklet on p15 of the fort at Drobeta with its potential 2 Praetoria. What you and others, however, have neatly presented throughout my research on the genuine hard archaeology evidence, is that many sites are not all, poorly or are simply no longer possible to excavate and identify the results more accurately.

I am sorry but I must say I find the one headquarter's building (Principia) for each unit ludicrous.
Here along our Limes a giant encampment for two Legions was found, not even having a headquarter's building, and what could have been it was not that enormous...(The Drusus/Tiberius encampment). In the LXG castra there was one large Principia. I think more along the lines that one building might have served several units in some instances.

The idea that only one building/house is found in some forts which is classified as a Centurio's mansion/house or officers house is also highly debatable. There are some large castra which have at the end of each barrack block a building that most of the times is explained as having been the officer's housing. Partly because the houses look more Romanesque with a courtyard. Only in Vindolanda we know fairly exact where the commander of Equestrian status lived and in what buildings his administration probably was located.

Also I do not agree with the idea that roof tiles were not transported in bulk along the line. We have more than enough proof in Germania Inferior that they were mass produced as well as shipped all along the line.

To state that there would only have been one officer's house, just like one headquarters building for each unit and basing your theories on that assumption alone is not proof in itself.

Just my two Asses.

M.VIB.M.