Kids and adults will enjoy the Su Nuraxi of Barumini. Well, maybe not grandma unless she has catlike maneuvering skills. But grandma should be able to see most of the site without those skills.
A nuraghe is basically a massive ancient castle. There are quite a few nuraghi scattered all over Sardinia.
This nuraghe dates back to the seventeenth century BC. That's old old. As time went on, a settlement formed around this one.
In order to enter the site, you will need to be on a tour. The tour guides speak a number of different languages. Most likely your tour will be given in both Italian and another language. It all depends on who is on the tour. The tour guides really give you a good idea of how they think the nuraghe was setup and used.
You'll walk through the settlement as you start the tour. At this point, you'll start to realize how skilled these people were at construction. They basically cut all the rocks so that they would perfectly fit together in such a way that they would be stable. They didn't have any type of cement like material to bind the rocks together. It's pretty amazing to see.
The settlement is basically a big maze of broken rock houses that the kids will enjoy running around in. If they get lost, just shout out in a medium level voice where you are. The place isn't that big. The kids will find you and most likely take off again to get lost.
After the settlement, you have to climb up a modern staircase to get to the top of one of the center towers. That's the only way to get in. The stairs going up to the top are easy. Going down into the tower is where you need to climb your way down. You'll be manoeuvring down the original stairs. You'll have to duck and wiggle a bit. Kids will love this part.
Once you are down on the ground in the center tower, there are a few cone shaped rooms and a corridor that links two of the cone towers. The tour guide will most likely be explaining everything to the group while the kids take off into the towers. The kids will have fun exploring. Don't worry though. They can't go anywhere. There is only one exit and that is up the same way you came down.
Last Bit of Advice
As you leave the site, ask one of the guides to point out a mirto bush. They are along the path as you walk back the ticket house. Mirto is used to cook with and also to make a traditional Sardinian drink. Break off a leaf and have a smell.
If you are at the Su Nuraxi around lunch time, take the family to the Hotel Su Nuraxi Ristorante. It is about 2 minutes away from the site driving. The food is excellent. Try the lamb. And for the adults, have a mirto after dinner while you watch the kids on the playground outside.