Why it looks like this

Algiers climbs from the Mediterranean up a steep slope, and its two histories sit one above the other. On the hill is the Casbah — the old citadel town of narrow, stepped alleys where cars cannot go, listed by UNESCO in 1992.

Below and around it, French colonial planners built a different city after 1830: arcaded boulevards along the waterfront, apartment blocks facing the bay, and ramps and tunnels to fight the slope. The white walls of both gave the city its nickname, 'Alger la Blanche' — Algiers the White.