The design approach of new additions is one of the most commonly discussed issues in the conservation field. Additions should be differentiated but compatible for achieving a harmony between new and old. Heritage buildings can be transformed into major landmarks of the city after conversions or may harm the originality and significance of the heritage buildings. Although there are international preservation standard and charters that introduce principles for interventions in historical context, they are not followed by some countries. Local authorities give permission to new developments that have been designed by Star architects, which can be inappropriate to historical context, to promote the district and the country. The paper questions the success of the selected designs by star architects in terms of architectural conservation principles that defined in the international preservation standards and charters. Selected case studies have been assessed through the identified principles from the selected international preservation standards and charters. New designs in historic environments should add another value to the heritage buildings rather than destroying its character and identity. The additions can be acceptable if it contributes to the city identity and if it does not damage the identity of the existing historic structure.