Scientific studies at Karacahisar Castle in northwestern Eskişehir province, which started with a surface survey for the first time in 1999, have been continuing with excavations. During the archaeological digs, a coin minted on behalf of Orhan Bey, also known as Orhan Ghazi (Turkish for war veteran), the second ruler of the Ottoman Empire, has been discovered.

Karacahisar was the first castle conquered from the Byzantine Empire by Orhan’s father Osman Ghazi, the founder and first sultan of the Ottoman Empire, in 1288.

During the re-evaluation of the archaeological data carried out simultaneously with the excavations by expert teams at the castle, it was understood that a coin that was recently unearthed actually dates back to the reign of Orhan Ghazi.

The coin is inscribed with the name of Orhan and the word "Tawhid," denoting the oneness of God.

Speaking to Anadolu Agency (AA), excavation team leader Hasan Yılmazyaşar said Karacahisar Castle holds an extremely important place in Ottoman history.

"One of the gratifying results for us this year is that for the first time the existence of a coin minted on behalf of Orhan Ghazi was unearthed in Karacahisar Castle," he said.

He added: "We know that there has been a settlement here since the Osman Ghazi period. Historical sources pointed out the settlement, but it had to be archaeologically proven somehow. In this sense, this coin of Orhan Gazi is extremely important to us."

"These were both pleasing and scientifically meaningful results as very important data for us to understand the history of the period and to define sociocultural and historical relations," he added.

They plan to continue excavations for about one-and-a-half more months, Yılmazyaşar said.