Say what you will about Arch 22, but it's still one of the best places to go get peace and serenity in Banjul (if not The Gambia). It's cool - that's the first thing you notice when you go there: this is one place the heat does not come in the evening, and this is almost like heaven after the humidity of the indoors.
Occupied Banjul does not have a lot of space left*. All the space on all the streets have been taken up with houses and garages and shops - on some streets there is barely enough room to fit two cars at once, let alone stand and look out at the brave horizon, as the sun sets beneath it. At the Arch though you have all the brave horizon you want - it's one of the few (if not the only) wide open space left in the city, and the ban on normal traffic within the Arch zone (a stretch of road beneath the Arch) greatly reduces the pollution on the main road, both of the noise and filthy air types.
*The emphasis here being on "Occupied" - Banjul has lots of space, but most of it is taken up by Mangrove swamps, and are empty of people and their habitation.