Born in Wormerveer, the Netherlands, in 1938, Maciel Kiel completed his doctoral dissertation at the University of Amsterdam in 1983, titled “Bulgarian Ecclesiastical Architecture and Mural Painting in the Turkish Period: A Sketch of the Economic, Juridical and Artistic Preconditions of Bulgarian Post-Byzantine Art and its Place in the Development of the Art of the Christian Balkans.” He was appointed professor in 1993.

Kiel undertook his first journey to the Balkans in 1959, followed by travels to North Africa, Turkey, and Iran between 1960 and 1961. From 1958 to 1976, he was involved in the restoration of various historic buildings and, through extensive research expeditions between 1969 and 1990, played a pivotal role in uncovering Ottoman architectural heritage across the Balkans. He conducted archival research in Istanbul, Ankara, and Sofia from 1979 to 1999.

Throughout his career, Kiel held teaching positions at institutions including Harvard University, Moscow State University, Munich, the Paris École des Hautes Études en Sciences Sociales, and Utrecht University. He served as a UNESCO consultant for Bosnia and Herzegovina and was elected a member of the International Committee of Dutch Byzantine Studies in 1972.

Kiel devoted many years to the Netherlands Institute in Istanbul (NIT), serving as director from 2003 to 2006 and subsequently as a senior researcher until 2020. He passed away on 29 July 2025 in Heemstede, the Netherlands, where he spent his final years.