Why it looks like this

Manaus stands where the dark Rio Negro meets the sand-coloured Amazon — the 'meeting of the waters', where the two rivers flow side by side without mixing for kilometres. During the rubber boom of the late 1800s it became one of the richest cities anywhere, importing electric trams and the Teatro Amazonas opera house.

The map shows a city that roads barely reach: streets end at forest and river, the port floats to ride the river's ten-metre seasonal rise, and most connections to the rest of Brazil are by boat or air. A free-trade zone since 1967 keeps two million people employed in the middle of the rainforest.