Roman Stone Overhead?

Home base during our recent trip to Provence was a place ambitiously called Provence Paradise .  Ambitious, but not inaccurate.  We had a delightful stay and I recommend the place.

The main building is a refurbished 17th century building once the home of the owners of a tile factory or "Tuilery".  There must have been some more generalized pottery being made on site as well, the walls have chunks of it built into them.

In any case the owner, an energetic fellow named William, learned of my interest in things Roman.  He pointed out a couple of walls that he thought might go back to Roman times, then showed me an inscribed stone built high up into the building.  He had been told that it was Roman, and had been relocated from the city wall of St. Remy.

The stone was high up in the wall-in fact it is on the outside of our second story bathroom wall-so my photo is not ideal.

My first thought was, well, maybe.  St. Remy was not thought to have had Roman era walls, but old stones sure get incorporated into medieval walls.  And a radiate pattern of stone work was not unknown in Roman times.  Here is an example from the Theater in Arles:

But there were some problems that soon presented themselves.  For instance, our possible Roman stone has as a central feature a crucifix in the modern style.  Not really used in the Roman era.

Even after Constantine legitimized Christianity the Chi Rho version was more prevalent.

Of course if you refer back up to the first picture you do see roman numerals.  I considered whether this might have some ecclesiastical import, perhaps something to do with Stations of the Cross.  But there are supposed to be 14 of these, and the inscriptions on the stone-at least the part available to me-only appear to go up to ten.  (in fairness the numerals to the right of  X are indistinct).

I also note the unusual progression of numbers.  Reading from left to right it at first glance looks like:

                                                                2   3  (cross)   9   10

but if you flip it upside down and use a little imagination it becomes

VIII   (IIIIV ?)   X   XI  (cross)   II   I   (?)

In fact, perhaps what I was seeing as a cross is simply the X in XII.  The next digit would then be I.  This seems to closely parallel medieval sundials.  Here are a couple.  

Our example has some quirks, and several numerals that can't be read at this range, but I am confident that this is a medieval sundial, perhaps from a church in St. Remy, although I saw a number of "architectural salvage" businesses about.  Sometimes it is hard to be certain of provenance in Provence. 

If you are curious about sundials, here is more.  Much more:  The British Sundial Society