Is a finite cyclic group a Poincare duality group?

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I am trying to understand whether the finite cyclic group of order $n$, $C_n$ is a Poincare duality group, i.e. whether it's classifying space $K(C_n,\,1)$ is a Poincare complex. I know that the classifying space of a cyclic group is a lens space, but am unsure whether a lens space is necessarily a Poincare complex.

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No. A Poincaré duality space must in particular have vanishing cohomology above some degree, but a nontrivial finite cyclic group has nonvanishing cohomology in arbitrarily high degrees.