A small but dedicated band of enthusiasts have spent 40 years practising sustainability at the thought-provoking CAT, set in the Dyfi Unesco Biosphere Reserve, north of Machynlleth. Founded in 1974 (well ahead of its time), the CAT is an education and visitor centre that demonstrates practical solutions for sustainability. There are 3 hectares of displays dealing with topics such as composting, organic gardening, environmentally friendly construction, renewable energy sources and sewage treatment and recycling.

　　To explore the whole site takes about two hours – take rainwear, as it's primarily outdoors. Kids love the interactive displays and adventure playground and there's a great organic wholefood restaurant. The visit starts with a 60m ride up the side of an old quarry in an ingenious water-balanced cable car (closed in winter to save water). A drum beneath the top car fills with stored rainwater and is then drawn down while the bottom car is hauled up. At the top you disembark by a small lake with great views across the Dyfi Valley.

　　There are workshops and games for children during the main school holidays and an extensive program of residential courses for adults throughout the year (day courses start at around £45). A new purpose-built education centre also offers postgraduate programs on sustainability, organic food production, renewable energy and sustainable architecture. Volunteer helpers are welcome, but you'll need to apply.

　　To get to the CAT from Machynlleth (seven minutes) you can take the 34 bus. Buses T2 and X27 go to the village of Pantperthog, a 10-minute walk away.