From Bonorva, follow the signs towards Bono (also signposted for the site) on the SP126 and then the SP43. About 6.5km from Bonorva take the right fork and proceed carefully - we hit the bottom of the hire car on a ridge and pothole combo and though fortunately nothing fell off, and no leakage occurred, it made some very nasty noises for the rest of the holiday and didn't do much for my nerves! - for another 2.5km. Park on the road by the big tree opposite the site.
Open 10:00 - 13:00 and 15:00 - 19:00 (all day in July and August, I think), entrance 3½ euros per person including guided tour of the main tomb - in Italian!
From the ticket hut, follow the path up the slope and double back on yourself past the steps and tombs to the "tomb of the head" which is locked when the site is closed. This tomb is deep and made up of several different rooms: the vestibule area has cists cut in the floor on the left and cupels the other side of a central rainwater channel. The two rooms behind each have two pillars and numerous side chambers, and on the ceiling you can see the original red paint, and later murals as the tomb was used through Roman times, and then used as a church, and was still in use in the Middle Ages. There are numerous friezes from its Christian period on the walls. There's also a light well, and the floor in the central chamber has been carved to collect the rainwater that this also lets in, probably used for baptisms.
You are free to wander around the rest of the site - to the right is tomb VIII with its carved roof, meant to resemble the rafters of a hut, and right from there in tomb IX someone's added graffiti "Ciao Lucy" in red paint.
The steps to the right lead to a small gate, and then a rock cut path to the hilltop, where you find more tombs / dwellings cut into the rock, and the rock cut dolmen, described as being known locally as "the Elephant" in TME, but also listed as a Taurus in my research.