Research Aim: This study intends to identify the role of modern architecture in smart and sustainable cities. It will show how modern architecture fits in the model of smart cities. It will shed light on the impact of modern architectural designs on the sustainability indicators of a smart city. Moreover, it will show how these designs help create an eco-friendly and easy town to commute to. It will use the case of Copenhagen, Denmark, to show how did they make a sustainable city by altering their architectural designs.