  In this paper we prove that for any prime $p\ge 11$ holds
  $$ {2p-1\choose p-1}\equiv 1 -2p \sum_{k=1}^{p-1}\frac{1}{k} +4p^2\sum_{1\le
i<j\le p-1}\frac{1}{ij}\pmod{p^7}.
  $$ This is a generalization of the famous Wolstenholme's theorem which
asserts that ${2p-1\choose p-1} \equiv 1 \,\,(\bmod\,\,p^3)$ for all primes
$p\ge 5$. Our proof is elementary and it does not use a standard technique
involving the classic formula for the power sums in terms of the Bernoulli
numbers. Notice that the above congruence reduced modulo $p^6$, $p^5$ and $p^4$
yields related congruences obtained by R. Tauraso, J. Zhao and J.W.L. Glaisher,
respectively.
