 At this time he also photographed the colonial Colombian city of Villa de Leyva and was mentored by Germán Téllez at the Universidad de Los Andes and William Zapata at the Colombo American Center.In 1972 Castro graduated with a Bachelor of Architecture from Universidad de Los Andes and moved to Eugene, Oregon to attend the School of Architecture and Allied Arts at the University of Oregon.There he was taught by Robert S. Harris, a proponent of participatory design, and worked during the summers of 1973-75 in the Campus Planning Office where Christopher Alexander's Pattern Language was implemented as "The Oregon Experiment".