Again, I wish TripAdvisor had a "good" rating between "average" and "very good."
I haven't seen a lot of ruins (so far just in Mexico and at Lake Titicaca) but insofar as ruins go these aren't anything spectacular, far from it. It's largely in shambles and so much still remains below ground. The "museum" is in a sorry state and they have used cement to reconstruct much of the above ground site, so it feels and looks a bit off.
Despite the lack of largesse, I have to say that I really enjoyed visiting Tiwanaku. Considering the low cost of the trip I'd say it's entirely worth it. Absolutely go with a guide/on a tour (as I did) so that you can get the story of the place. And don't be chintzy, eat the overpriced tour lunch, buy a knick-knack, support the local economy, and be a gracious guest in the ancient lands of Bolivia : ) The whole thing will probably cost you less than the price of a couple of beers or a cinema ticket at home.
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