The flag of Albania is a red flag with a black double-headed eagle positioned in the centre. The red colour used in the flag symbolises the bravery, strength and valour of the Albanian people, while the black colour appears as a symbol of freedom and heroism. The eagle has been used by Albanians since the Middle Ages including the establishment of the Principality of Arbër and by numerous noble ruling families such as the Kastrioti, Muzaka, Thopia and Dukagjini. Gjergj Kastrioti Skënderbeu, who fought and began a rebellion against the Ottoman Empire which halted Ottoman advance into Europe for nearly 25 years, placed the double-headed eagle on his flag and seal.