Question: Which one, Boğaziçi University or Basilica Cistern, was built in the 6th century during the reign of Byzantine Emperor Justinian I?
Sentence (from "Sarosius"): From the latter we learn that the Avars whom Sarosios helped in 557 were in fact renegades from the Hephthalites (who surrendered to the Göktürks and Sassanid Persia in 567) and apparently had no right to use the title of Avar Khagan.
Relevant evidence: No