Eden Project, Cornwall

The Eden Project is a striking day out built inside a former Cornish clay pit, where two enormous biomes recreate rainforest and Mediterranean climates. The Rainforest Biome, one of the largest indoor rainforests in the world, is the standout, with a lofty canopy walkway and a genuinely humid jungle feel that children find thrilling. Outdoor gardens, seasonal activities and a strong programme of family events round out the day. A useful quirk of Eden's pricing: its standard General Tickets are also annual passes, giving you unlimited return visits for a whole year at no extra cost, so a single trip works out well if you are holidaying nearby. Advance online prices are around £35.50 for adults (16+) and £12.50 for children (5-15). It is a fair trek for anyone outside the South West, so it works best as part of a Cornwall holiday. The Rainforest Biome gets warm, so wear layers you can peel off.