Thiesi lies on a low calcareous plain on the eastern slopes of the Su Montiju plateau. The territory has been inhabited since at least the Neolithic Age, while the inhabited centre sprang up during the period of Roman domination, modifying its urban layout over the course of the centuries and developing into two distinct zones: the first around the Church of Santa Vittoria, and the second around the seventeenth century Church of Sant'Antonio. Until a short time ago, the village had a sort of triangular-shape, with the Sanctuary of the Madonna of Seunis, the monastery with the Church of San Sebastiano and the Church of San Giovanni in Badde Serena lying at its vertexes. According to a legend, the afore-mentioned Patron Saints, while all the other nearby villages were infected by outbreaks of the plague and cholera, protected the village from these diseases spread by two devils.
The etymology of the name can probably be traced back to the Sardinian adjective "tiesu", which means 'stretched' or 'extended', while the historian, G. Spano, suggests that it derives from the Phoenician term "bethiezi" (house of my fortress), but many scholars retain that this hypothesis is unlikely. A number of sources suggest that Thiesi was founded by the Jews deported here by the Romans. Nowadays, the economy of the village is based above all on cheese and milk production and on the exportation of typical products like pecorino romano (ewe's milk cheese). Craftwork production is also interesting with articles made from the working of leather, wool, wood and from weaving. Leaving along the main road from the centre of the village, we find the Parish Church of Santa Vittoria, a wonderful example in Gothic-Aragonese style erected at the beginning of the sixteenth century. The fine rose window is typically Gothic, while the refined decoration and the architraved portal, with its reliefs in rather more popular tones, are in a more classical style. Another church to visit is that of Sant'Antonio of Padua, erected in around 1650, the fulcrum around which the second urban centre of the village has developed. "Sa treighina" is recited here every year. A mural by the great Sardinian artist, Aligi Sassu, can also be admired on the building housing the Middle School. The artist lived right here in Thiesi for a number of years and also opened a studio. The mural recalls "s'annu de s'attaccu" (the year of the assault, namely, 1800) when the troops of the lord of the village, the Duke of Asinara attacked the inhabitants who had refused to pay his taxes. On the outskirts of inhabited centre, the Sanctuary of the Madonna of Seunis, a destination for the Mariani pilgrimages, rises on a rocky outcrop dominating the valley of the Rio Molinu.
The sanctuary was built in the eighteenth century with later modifications. According to tradition, a farmer while ploughing his field, found a box containing the statue of the Madonna. After this discovery, the farmer, encouraged by all the villagers, offered his field to the Madonna and started building the sanctuary. The statue is still to be found today inside a small nineteenth century throne. The Feast of the Madonna of Seunis is celebrated on 8th September and attracts a great number of pilgrims. The final church that should be visited is the Church of San Giovanni, which is found in a marvellous valley rich with vegetation and reachable along a steep stone staircase. The feast is celebrated on 24th June and is organised by the young people of Thiesi. The so-called "fogarone de Santu Giuanne" is very characteristic, a huge bonfire lit on the evening of the vespers. A short car-ride away from Thiesi, lies the Mandra Antine hypogeum, several 'domus de janas' (chamber tombs), dating from the III millennium BC, which take their name from the most famous tomb, also known as the 'painted tomb', characterised by decorations and brightly coloured frescos in gold, red, vermillion and black. The tomb is closed by a fence and can only be seen through a gate. to enter the tomb you need to ask the Thiesi council for the key. Just outside the village, the Fronte 'e Mola or Su Saccu Protonuraghe is found on the edge of a little wood of cypress trees. The monument is hidden by vegetation and is thus difficult to see from afar. For anyone wishing to take a trip among the flavours of the Meilogu area, Thiesi offers a selection of succulent dishes which range from the "impanadas", little timbales of pasta filled with pork seasoned with nutmeg and saffron, to "su succu", a first course made with hard-wheat bran and 'fregola' (Sardinian toasted pasta) cooked in sauce or broth or su ghisadu, namely, lamb cooked in tomato sauce.