A dramatic increase in the city's urban sprawl began in the nineteenth century, when labourers flocked from the countryside to work in the new factories that were then springing up. Large developments of small terraced houses began to appear and the new public transport systems – (the metro, buses and trams) – allowed workers to commute into the city daily. Suburban districts also sprung up around the city centre to accommodate those who wanted to escape the squalid conditions of the industrial town.