The dead centre of town
The roads actualy dissect the city into four and act as a very efficiant barrier to getting around if you don't have a car - as the vast majority of people who live there don't.
It never really caught on as a place to live though and at weekends it's close to deserted, apart from the market which springs up unofficially next to the banking sector, near the central interchange.
The main east-west route is closed on Sunday, I think it was used as a race track because it was so empty. But this means you can now expolore the lower level of the GSJ in the centre on foot and it's a very strange place to walk through!
Bassilia is in the middle of nowhere (which is why it never caught on as a place to live) and it takes 24 hours by bus over largely unmade roads to get there.
You can see my account of the 2001 trip here