If you shoot a tall building from close range with a wideangle lens, often you’ll need to tilt the camera to get the top of the building in shot. This causes converging verticals, where the sides of the building lean inwards. The effect can look fantastic if you exaggerate it, but if you want the building to look upright, you need to keep the camera back parallel to it by the following methods.
Shooting from a higher viewpoint so you’re looking across at the building can work. Moving further away from the building then zooming in is another option, as the effects of converging verticals are reduced with distance. Alternatively, correct the convergence in Photoshop. Go to Select>All, then Edit>Transform>Distort and pull the corners of the image up and out to straighten the sides of the building. Using View>Show>Grid can help ensure the verticals are truly vertical.