This research examines the concept of uncomfortable heritage sites, and analyse how sustainable development can be attained through utilising adaptive reuse for sites associated with atrocious events. The research starts with a thorough analysis of key issues; uncomfortable heritage and its cultural significance, heritage adaptive reuse, and last but not least, sustainable development. Three aspects of sustainability were chosen for this study; environmental, economic and most importantly cultural sustainability. The resulted research created a framework in which an application of comparative analyses between the cases were employed, which are Haus des Meeres in Vienna, The Energy Bunker in Hamburg and Boros Collection in Berlin. The research concluded that adaptive reuse of uncomfortable heritage contributed to the sustainable development in various ways; however, due to the sensitivity of this type of heritage, it is very important to conduct a comprehensive analysis on the site before adaptively reusing it.