Mosul’s Old City, where Iraqi forces are closing in on the Islamic State group’s final urban refuge in Iraq, is an ancient maze of narrow alleys.

At its heart lies the emblematic Al-Nuri mosque, where jihadist supremo Abu Bakr al-Baghdadi declared a caliphate in June 2014 after his forces seized Iraq’s second city along with swathes of territory extending into neighbouring Syria.

Baghdadi’s cross-border “caliphate” has been shrinking steadily since mid-2015.

The loss of Mosul would leave Raqa, in Syria, as the group’s only major urban stronghold.

Perched on the bank of the river Tigris and protected for centuries by 11th century ramparts, medieval Mosul was a key meeting point for merchants from India, Persia and the Mediterranean.

Today, the three-square-kilometre (one-square-mile) district is a maze of alleys lined with stone houses, small shops and the workshops of local carpenters, weavers and metalworkers.

It contains numerous markets, churches and mosques, the most emblematic of which is the Great Mosque of Al-Nuri.