We present the complete solution of the following problem of G. Pólya: Circular forest has a center at the origin and radius $R\geq 1$. A person is staying at the center and the trees of the radius $r$ are planted at all other lattice points of the forest. Determine the maximal value $\rho$ of the radius $r$ for which the person can see out of the forest and, in the case $r=\rho$, determine the directions in which he/she should look in order to see out of the forest.