Why it looks like this

Mosul grew for centuries as a dense walled city beside the Tigris River, its old quarters a maze of narrow lanes. As the city expanded in the 20th century, new districts like al-Mawşil al-Jadīdah — literally 'New Mosul' — were laid out with wider, more regular streets.

So the map shows two cities in one: the tight organic knot of the historic core near the river, and the looser planned blocks of the modern districts spreading away from it.