This thesis focuses on the multiple and final conversion of the former Roman Catholic Church Holy Ignatius to the Fatih Mosque. The church was built in 1929 by the architect Hendrik Willem Valk in Amsterdam and after many failed conversions the building transformed from a private meeting space for the socialists to its final form; the Fatih Mosque. After all these years of the building not being used after their commercial renters, the Turkish Muslim community bought it in the early eighties and transformed it into a Mosque. The transformation process was based on respecting and preserving the building’s architectural heritage while adapting to its new function. This case study shows how the mosque serves as an important cultural and religious center for the community (especially the Turkish/Dutch community) and neighborhood, symbolizing successful adaptive reuse of a historical monument.