Ten of us booked with MartulliViaggi.com for a guided walking tour of the Sassi of Matera, Sasso Caveoso and Sasso Barisano. The person in the group managed to haggle the price down. I guess size does matter.
The Sassi have been inhabited since 7000BC. Some families have been living in the same "house" for 9000 years. Those living in the "new", elevated part of the city (circa 1700), Civita, were more than happy to have the people of the Sassi living in poverty, because they were cheap labour. However, living conditions were appalling, and Matera was the shame of Italy. When World War 2 ended, the government in Rome stepped in and forced change. Most, if not all, of the 17,000 inhabitants were relocated to modern dwellings.
The Sassi are three sedimentary rock canyons. Caves were formed over time, and people moved in. Since the rock was soft, the caves were expanded by digging down. The temperature in the cave would be about 16 °C. They keep their animals in there, as well, which would provide some warmth. Families were huge (people didn't live long). Bigger caves implied more wealth.
The people didn't have any money and didn't associate with those living at the top of the canyons. Their language was primitive, with seven dialects. Relocating the people also meant teaching them about everything that we take for granted.
The material excavated from the caves was used to build structures outside of the caves. It all developed organically.
Some people still live there, but while there is electricity and running water, don't count on anything else. There are virtually no roads to speak of, and it is a vertical community, so you will get your stair count in quite easily. Don't get injured because you will likely need a helicopter to get you to the hospital.
The tour covered much of this, which you would miss if you wandered around. We also visited a "church" and a dwelling during the tour. Bring your comfortable walking shoes.