The uprights of the Stonehenge Great Trilithon are 40 tons each. The whole Trilithon totals 90 tons.
A 200 ton lump is more than I, the taxpayer, am happy to pay for if I'm expected to, unless there's a very good reason for it.
I don't think the taxpayer has to pay for anything at the Eden Project unless they visit it. Which I do recommend incidentally.