This work is dedicated to the 900th anniversary of the great victory of the Georgian people in the Battle of Didgori. Based on the comparison of Georgian and foreign narratives and other materials against the general background of the history of Georgia in the XI-XII centuries, the monograph presents important events of the reign of David IV the Builder. Particular attention is paid to the causes and consequences of the Didgori battle, the conquest and return of Tbilisi, the capital to the United Kingdom of Georgia.