The usual advice for landscape photographers is to shoot in the early morning or early evening when the sun is low in the sky. Urban landscape photographers have more flexibility – depending on the subject you can shoot at almost any time of the day or night.
However, early morning is still one of the best times. The low sun has a golden glow that adds warmth to brick and stone. It also gives a pleasing reflected light. Including the sun in the photograph, perhaps between a couple of tall buildings, can be effective.
As the day progresses and the sun rises in the sky, shadows shift across the subject creating interesting patterns of light and shade. If you have the opportunity, take a sequence of images from the same camera position at intervals during the day – this is easiest to do if you have access to an office or house overlooking an urban scene. Shoot from early morning to late evening. The resulting pictures will show the change in light during the day. This can be dramatic, especially if the scene is illuminated at night and you continue shooting into the late hours.