Sarah Parcak is an archaeologist who uses satellite imagery to identify previously unknown ancient sites that might be worth excavating. We've seen her in a couple of programmes about Ancient Egypt, because she's discovered the probable sites of several new pyramids as well as some towns. Rome's Lost Empire was presented by Dan Snow and showed us the sites Parcak found when she used her technology to investigate the Roman Empire.
I'll start with my criticism of the programme & get that out of the way - it felt more like a Discovery Channel programme than a BBC one. The narration by Snow was full of superlatives - everything was the most important whatever, or the best or the biggest. And they were setting out on a journey to solve a mystery! Which would revolutionise Roman archaeology and history forever! And now we have proof that this was the best something in the history of somethings! Which is ... not a style I'm particularly fond of in documentaries. Particularly because every time someone announces that "this evidence proves X" I immediately start coming up with explanations Y, Z, α etc that might also fit the data. What's wrong with a sober assessment of the probable explanation, with appropriate caveats and reservations. And it was unexpected, as I've not had that problem with previous programmes that Snow has presented. He did have some good lines tho, and the less bombastic stuff was good.
So we were treated to a mystery to be solved - how did Rome control such a large empire with such a relatively small army of professional soldiers (~300,000)? And this was the thread that tied together their investigation of four different areas of the Roman Empire - Rome's main harbour (Portus), an army encampment in Transylvania, the area around Petra in Jordan and the North African Wall. I don't think they really came to any conclusions, but it provided a lens through which to look at each area.
They also wove the programme together by splitting up the stuff about Portus and spreading it throughout the whole programme. I'm going to talk about it all at once though, as that's easier. This was the area where Parcak had the most trouble with her technology as the site of the harbour is pretty close to the current airport, and those bits not under runways are pretty populated. However she did manage to find indications of three new sites. The first of these was probably a canal - it was previously known that there were canals between the River Tiber & the harbour, this is the first evidence of one that ran from the other bank of the river up to Rome itself. Which would be a great help in both getting ships to Rome fast (on a straight line path rather than the winding river) and in managing traffic flow on the waterways to Rome. The second of her potential sites was an oval shape, positioned in the land near the waterways & harbour proper - this was the right size & shape to be an amphitheatre, providing entertainment to the people who lived and worked there. And the third was potentially the base of the Portus Lighthouse, which is known of but has never been found. If they can excavate that and confirm it then that's a pretty exciting discovery.
The Portus segments also showed us some of the excavation work that is going on there. They had some pretty neat CGI to show us what the buildings they're finding would look like superimposed on the actual landscape (with Snow, Parcak & the archaeologists they're talking to standing there in front of them too - it looks pretty real). The harbour and its buildings were build not just for functionality but also to impress. So this was part of how Rome exerted control - by looking like it should be in charge.
The first of the non-Portus segments was about a site in Transylvania. When the Romans conquered Transylvania they first had to start by crossing the River Danube at a point where it's about a mile across and has treacherous currents. So being the engineers they are, they built a bridge - it took two years, and as Snow pointed out, the psychological impact of this bridge being inexorably extended across the river to allow the Roman army to invade must've been considerable. Once conquered Transylvania had to be pacified, and there have been remains of Roman forts found in the dense forest of the region. They went to one of these, which is reasonably small - it would've been able to house about 1500 troops. Parcak then went up in a plane to use a technology called LIDAR to generate a map of what the landscape of the area around this fort looked like under the trees - I didn't really understand the description of LIDAR, I think it's a bit like RADAR but with lasers and somehow they can subtract the reflections from the trees and just look at the reflections from the ground. This allowed Parcak to identify what looked like a wider fortification around the known one, capable of housing a great number more troops on a temporary basis. They then trekked through the forest to see if it was really there (it was). That bit was a little amusing - they set off walking in a line, a couple of local archaeologists, Snow, Parcak ... and a man with a gun. I guess the local wildlife is still pretty wild. Anyway, this segment illustrated conquering and controlling by armed force.
The next section was about Petra, and of course we were treated to them riding through the well known bit. The surrounding area is more desert like (now) and so Parcak's tech worked well - she identified several square sites that looked to the eye of the local archaeologist as if they were potentially farmsteads. So they went out to visit one to have a preliminary look at the sorts of pottery you could find. This mean we had an amusing bit with Snow (a historian, not archaeologist) saying the sort of things we all think about how the ability of archaeologists to date pottery just from small fragments is astonishing & faintly magical. And then we saw Parcak and the other archaeologist confidently pick up a handful of broken bits of pot & say this was definitely occupied during Roman times :) This segment was illustrating "conquering" an area not using military force - Petra was not only agriculturally rich in ancient times, but was also on the trade routes from the Arabian peninsula into the rest of the world and rich from charging tolls. Effectively the Romans extended their protection and help with enforcing the tariffs in return for a cut of the proceeds, and so everyone was happy.
And the last segment was about the North African Wall - which ran along the edge of the fertile North African plains to protect this farmland from the nomadic tribes to the south. This (like Hadrian's Wall) wasn't a hard & fast boundary that no-one was allowed to cross, instead it was permeable and allowed traders and civilians to go to & fro whilst providing a barrier to opportunistic raiders. The local archaeologist they met up with in Tunisia took them to see a part of the wall, and they discussed how hard it was for him to find where the forts that he knew must be there were in what is now a trackless desert area. Parcak's imaging allowed her to pinpoint 30 or so square sites that looked like they might be fortifications and so they drove out to one. It had clearly been dug over by locals at some point, but one of the deep holes left showed them that there were centuries of occupation (and again pottery told them this was during the Roman era).
So while I took exception with the language of "we've proved X, we've solved mystery Y", this programme did show us how Parcak's imaging technology had provided four teams of archaeologists with new, potentially exciting sites to excavate. And they wouldn't've discovered them anywhere near as fast by searching the old fashioned way by driving or walking over the land.