ible ▁effect ▁on ▁global ▁affairs ▁through ▁so cio e conom ic ▁means . ▁The ▁term ▁has ▁become ▁increasing ly ▁familiar , ▁because ▁of ▁the ▁rise ▁of ▁global ization ▁( i . e ., ▁global ▁fin ance , ▁communic ations , ▁and ▁travel ). ▁An ▁attempt ▁to ▁define ▁and ▁categor ize ▁world ▁cities ▁by ▁financial ▁criteria ▁was ▁made ▁by ▁the ▁Global ization ▁and ▁World ▁C ities ▁Research ▁Network ▁( G a W C ), ▁based ▁primarily ▁at ▁L ough borough ▁University ▁in ▁England . ▁The ▁study ▁ranked ▁cities ▁based ▁on ▁their ▁provision ▁of ▁" ad vanced ▁producer ▁services " ▁such ▁as ▁account ancy , ▁advert ising , ▁fin ance ▁and ▁law . ▁The ▁invent ory ▁ident ifies ▁three ▁levels ▁of ▁world ▁cities ▁and ▁several ▁sub - ran ks ▁( see ▁Ga W C ▁study ). ▁ ▁A ▁metropol is ▁is ▁not ▁necessarily ▁a ▁global ▁city — or , ▁being ▁one , ▁it ▁might ▁not ▁be ▁among ▁the ▁top - ran king — due ▁to ▁its ▁standards ▁of ▁living , ▁development , ▁and ▁infrastr ucture . ▁A ▁metropol is ▁that ▁is ▁also ▁a ▁global ▁city ▁is ▁a ▁global ▁metropol is . ▁ ▁Africa ▁ ▁Egypt ▁ ▁C airo ▁and ▁Alexand ria ▁are ▁considered ▁Egypt ' s ▁biggest ▁metropol ises . ▁ ▁Niger ia ▁ ▁Lag os ▁is ▁the ▁most ▁popul ous ▁metropol is ▁in ▁Niger ia ▁as ▁well ▁as ▁in ▁Africa . ▁ ▁South ▁Africa ▁ ▁In ▁South ▁Africa , ▁a ▁metropol itan ▁municipality ▁or ▁" Category ▁A ▁municipality " ▁is ▁a ▁municipality ▁which ▁executes