In just under a fortnight, leaders from some of the world's major economies will gather in South Africa's economic heartland, Johannesburg, for the G20 summit.

But just a few kilometers from the spruced-up, highly secure venue is a city center that authorities struggle to improve and keep safe.

They face major challenges in cleaning up more than 100 derelict buildings, many plagued by rubbish and open sewage, some taken over by criminal gangs.

There's guns, there's drugs, there's prostitutes, there's everything here, said Nelson Khetani, resident of a building known as MBV1, located in Joubert Park.

Neglect and a lack of maintenance have left vandalized communal kitchens stripped of their fittings, while overflowing human waste covers parts of what used to be the laundry area.

Khetani told the BBC that rooms in MBV1 had been hijacked; a phenomenon where spaces or entire residential units are taken over and controlled by criminals to collect rent for themselves and sometimes provide a base for illegal activities.

The BBC has located and confirmed there are 102 derelict or abandoned buildings in the inner city, but other reports cite much higher figures. Many of these buildings are unfit for habitation.

President Cyril Ramaphosa expressed concern about the city's state earlier this year, stating, I found the city filthy.

Johannesburg's ongoing challenges in addressing these issues persist amidst the preparations for the G20, highlighting the stark contrast between the international summit and the lived realities of its residents.