A turbine airfoil comprising: a generally hollow airfoil body formed by an outer wall extending span-wise along a radial direction, the outer wall comprising a pressure side wall and a suction side wall joined at a leading edge and a trailing edge, wherein a chordal axis is defined extending generally centrally between the pressure side wall and the suction side wall, and an impingement structure (26A, 26B) comprising a hollow elongated main body positioned in an interior portion of the airfoil body and extending lengthwise along the radial direction, the main body defining a coolant cavity therewithin that receives a cooling fluid, wherein the main body is spaced from the pressure side wall and the suction side wall, such that a first near wall passage is defined between the main body and the pressure side wall and a second near wall passage is defined between the main body and the suction side wall, wherein a plurality of impingement openings are formed through the main body that connect the coolant cavity with the first and second near wall passages (72, 74), for directing the cooling fluid flowing in the coolant cavity to impinge on the pressure and/or suction side walls (16, 18), characterised in that the impingement structure (26A, 26B) is manufactured integrally with the airfoil body, the coolant cavity extends radially between first and second ends (36, 38), wherein the first end is open, being connected to a cooling fluid supply external to the airfoil body, and a tip cover is disposed at the second end, and in that the second end is located in the interior portion of the airfoil body, terminating short of a radially outer tip of the airfoil body. a generally hollow airfoil body formed by an outer wall extending span-wise along a radial direction, the outer wall comprising a pressure side wall and a suction side wall joined at a leading edge and a trailing edge, wherein a chordal axis is defined extending generally centrally between the pressure side wall and the suction side wall, and an impingement structure (26A, 26B) comprising a hollow elongated main body positioned in an interior portion of the airfoil body and extending lengthwise along the radial direction, the main body defining a coolant cavity therewithin that receives a cooling fluid, wherein the main body is spaced from the pressure side wall and the suction side wall, such that a first near wall passage is defined between the main body and the pressure side wall and a second near wall passage is defined between the main body and the suction side wall, wherein a plurality of impingement openings are formed through the main body that connect the coolant cavity with the first and second near wall passages (72, 74), for directing the cooling fluid flowing in the coolant cavity to impinge on the pressure and/or suction side walls (16, 18), characterised in that the impingement structure (26A, 26B) is manufactured integrally with the airfoil body, the coolant cavity extends radially between first and second ends (36, 38), wherein the first end is open, being connected to a cooling fluid supply external to the airfoil body, and a tip cover is disposed at the second end, and in that the second end is located in the interior portion of the airfoil body, terminating short of a radially outer tip of the airfoil body.