In reality, to be precise, La Paz cannot be dissociated from El Alto ; if the Bolivian capital is cramped at the bottom of its valley, its twin city, which stands on the plain above it, serves as a reservoir of population: half of the population, the most modest, lives there. The two cities, blending indistinctly into each other, meet on the steep slopes (800m of difference in altitude!) that go up to El Alto -or down to La Paz, as you prefer.