"Knyaginya Klementina" was a school on the place where "Saints Cyril and Methodius" School is now. It was named after Tsar Ferdinand's mother. Interesting fact, there had been held religious services before the church "Saints Cyril and Methodius" was built.

source: the Facebook group "Old Burgas"

published by: Mihail Hadziyanev

(see comments here)