As other reviewers have said, you need to be a bit agile to get into the interior of the towers and wear appropriate shoes. But if you are agile, but a bit nervous, go try it. We are in our 70's and did just fine. My husband is 6'2" and there was one spot where he had to twist slightly, but it was not constrictive. There are only two places where you cannot stand up straight and yet the area feels spacious. So- coming into the main tower complex, you climb metal stairs (see photo), continue into a crevice/tunnel. This whole passageway is about 20 to 30 feet in length; the first 15 feet are slightly downhill and uneven. This is followed by 10-15 feet of a climb down which ends on the top of the metal stairs. This is the portion that is a bit of a challenge to most, but no one asked for help. Then you climb down to the floor of the tower on the metal stairs. This area of the tower is open to the sky. From this entrance 'hall', you can peek into adjoining chambers without entering. There is a large room off this space, that is lit up and whole tour groups enter without being constricted and this is reached by a passageway about 8 to 10 feet long (see photo) and it is open to the sky. From this room, there is another room to visit that is essentially a dead end storage space. Return to the lit up chamber to access the hall with the metal stairs. You cannot get lost in these rooms. Climb back up the stairs, through the 20-30 foot passageway to the exterior metal stairs. There is a metal pathway to the back of the tower where you can go to take more photos from the top. Then back down the stairs! And YOU DID IT.
Additionally, at the bottom, you might turn a sharp left and follow the path around the exterior of the tower. I enjoyed the quiet of that small walk as no one else did it. I was able to imagine what it might have been like when this was inhabited.
I do want to express reservations about who probably should not try and do this. If your hands cannot grip the handholds, don't go unless someone strong is there to help you. If you are wearing white/light pants, don't go. If you have inappropriate foot wear, don't do it.
If you are like me and determined to see what is to be seen. you can get down the interior passageway (the last portion to be climbed down) on your buttocks. It all depends on how determined you are.
If you are with a tour group, try to be last in line. Also be cognizant of the fact that once a tour group begins through, you have to wait for the last person to exit the passageway before you can go in the other direction.
We toured with an archeologist and he recommended the book "Su Nuraxi in Barumini" by Giovanni Lilliu, who discovered/ and worked this site. The book (in English) is scholarly but bit by bit I am conquering it. It is available at the gift shop, as is a harming miniature clay tower...