Istanbul University, Institute of Biology (currently known as Botany Division), designed with a functionalist style by Swiss-Austrian architect Ernst Egli, was built in 1935 in Süleymaniye. The Institute and (Alfred Heilbronn) Botanical Garden were of great importance to meet necessary technical and architectural aspects of contemporary biology education for the first time in Turkey. The land on which the institute was founded, where Ağa Gate, Bab-ı Meşihat and old Istanbul Girls' High School were located before, has become an important part of the 20^th century modern architectural heritage by having a place in the memory of the city with events, structures, people and plants, which emerged under the influence of social and political dynamics in the Republic period. The Institute of Biology located in the ‘Süleymaniye Mosque and its Associated Component Area’, which were inscribed on the World Heritage List in 1985, is currently on the agenda as a controversial subject due to the evacuation of the Division and Botanical Garden and their allocation to the Istanbul’s Mufti's Office. This study draws attention to the historical values and current potentials of the building and garden on the basis of preserving the modern architectural heritage.