A vertical axis wind turbine comprising: - a rotor having a substantially vertical rotation axis z, said rotor comprising a plurality of blades arranged to rotate about said rotation axis z in consequence of an aerodynamic drag opposed to an air flow investing said blades; - a casing structure in which said rotor is housed, said casing structure comprising: - a lower plate substantially orthogonal to said rotation axis z, said lower plate defined by a first plurality of vertices V 1,...,V n; - an upper plate substantially orthogonal to said rotation axis z, said upper plate defined by a second plurality of vertices V 1 ',...,V n ', each vertex V 1 ',...,V n ' of said second plurality corresponding to a vertex V 1,...,V n of said first plurality; - a plurality of walls (125a-125d) arranged to connect said lower plate and said upper plate, said walls (125a-125d) and said plates (121,122) defining a plurality of openings (126a-126d) through which said air flow is arranged to enter/exit said casing structure; each wall (125a-125d) of said plurality of walls defined by a respective edge (127a-127d) arranged to connect a vertex V 1,...,V n of said first plurality with a corresponding vertex V 1 ',...,V n ' of said second plurality, each said edge (127a-127d) having a profile protruding outwards from said casing structure, said protruding profile arranged to protrude beyond a corresponding straight line V 1 -V 1 ',...,V n -V n ' connecting said vertex V 1,...,V n of said first plurality with said corresponding vertex V 1 ',...,V n ' of said second plurality, in such a way that when an entering air flow enters said casing structure through a first opening, said protruding profile of said edge generates the separation of a portion of flow from said wall creating, at a second opening adjacent to said wall opposite to said first opening, a low-pressure zone that increases the flow rate of said entering air flow that enters said casing structure, said wind turbine characterized in that said edge (127a, 127b, 127c, 127d) has a curvilinear geometry with concavity oriented towards a respective opening (126d, 126a, 126b, 126c). - a rotor having a substantially vertical rotation axis z, said rotor comprising a plurality of blades arranged to rotate about said rotation axis z in consequence of an aerodynamic drag opposed to an air flow investing said blades; - a casing structure in which said rotor is housed, said casing structure comprising: - a lower plate substantially orthogonal to said rotation axis z, said lower plate defined by a first plurality of vertices V 1,...,V n; - an upper plate substantially orthogonal to said rotation axis z, said upper plate defined by a second plurality of vertices V 1 ',...,V n ', each vertex V 1 ',...,V n ' of said second plurality corresponding to a vertex V 1,...,V n of said first plurality; - a plurality of walls (125a-125d) arranged to connect said lower plate and said upper plate, said walls (125a-125d) and said plates (121,122) defining a plurality of openings (126a-126d) through which said air flow is arranged to enter/exit said casing structure; - a lower plate substantially orthogonal to said rotation axis z, said lower plate defined by a first plurality of vertices V 1,...,V n; - an upper plate substantially orthogonal to said rotation axis z, said upper plate defined by a second plurality of vertices V 1 ',...,V n ', each vertex V 1 ',...,V n ' of said second plurality corresponding to a vertex V 1,...,V n of said first plurality; - a plurality of walls (125a-125d) arranged to connect said lower plate and said upper plate, said walls (125a-125d) and said plates (121,122) defining a plurality of openings (126a-126d) through which said air flow is arranged to enter/exit said casing structure;