(S (S (NP (BASENP (DT The) (JJ inner) (NN circle)) (PP (IN of) (BASENP (NNS bluestones)))) (VP (VBP are) (NP (BASENP (DT the) (JJS earliest) (NN stone) (NNS structures)) (VP (VBN found) (PP (IN in) (BASENP (DT this) (NN site))))))) (PERIOD .))