We visited Galli recently, one teenager and three adults. It was most interesting and entertaining. they are recreating a 9th century monastery compound using only building methods and materials from that era. There are carpenters, stone masons, a black smith etc. There is even a market place with ye olde drink, and food. (but with 21st century hygiene I stress and they have nice very clean loos). There is a market stall selling super hand made items.
The people who work there are mainly volunteers, they are all so friendly, and willing to let you 'have a go' at being a carpenter etc, if you want to,
Most speak English and there is an English leaflet to help to. It is all laid out very well and not too big. there is a a small shop at the entrance selling ice-cream, and small nick knacks. A very enjoyable experience. you can take a couple of hours or all day, depending on how long you spend at each section. Highly recommended. suit all family members, and is set in the forest, so there is some shelter from the sun. very reasonable price to get in.

Entrance fee is 9,00Euro, which is cheap for this area.
Free, ample parking close to the site entrance.
My wife and I thought this would be a quick visit but actually spent 6 hours at the location. This project is still in the development stage but there is already much of interest. Everything in the project uses only the arts, crafts and materials available at the original historical time. All people involved in realizing the project are unpaid volunteers but many are skilled craftsmen in real life.
Don't be afraid to ask questions, most "workers" speak very good English and enjoy giving detailed and knowledgeable answers. There is ample refreshment available in the Market Square. We will be definitely be frequently returning to measure the progress. The visiting school-age children we saw were enthralled with most of the site attractions.