¡i©ú³ø±M°T¡jNo two cities are alike, but our conceptions of a ''livable'' city do not differ much. World Cities Day, which is today, celebrates the ideals of urban life.

Basic facts

Date: 31 October

Year of designation: 2013

Designated by: the United Nations General Assembly

Aim: to recognise the significance of urban basic services as a foundation for overall social and economic development

¡»The importance of urban planning

Urban planning is a focus of World Cities Day. It is crucial to a city's livability. Urban planning is the process aimed at improving the urban environment and achieving certain social and economic objectives. According to the UN, planned urbanisation ''maximizes the capacity of cities to generate employment and wealth and to foster diversity and social cohesion between different classes, cultures, ethnicities and religions''.

The UN believes that urban planning should be carried out not only to generate jobs and opportunities but also to help build socially integrated, livable, open neighbourhoods; that it should enable residents from different backgrounds and income levels to live together; that it should promote everyone's equal access to services, jobs and opportunities; that it should enable equal access to land, food and water for all; and that it includes public spaces, parks, playgrounds, streets with pedestrian space and commercial activities so as to create a vibrant public life for all residents.

What makes a city more "livable" ?

Every year the Economist Intelligence Unit (EIU), the corporate cousin of The Economist (¡m¸gÀپǤH¡n) magazine, ranks cities worldwide according to liveability. Each city is judged by five criteria: stability, healthcare, culture and environment, education and infrastructure.

Barcelona ¡V a successful urban planning story

Barcelona's expansion in the 19th century is often cited as a classic example of urban planning. In the mid-1850s, the city was on the brink of collapse. Its crowded population was confined by a medieval wall. The mortality rate was high. After the walls had been demolished, the government looked for plans to expand the city.

The project was handled by Ildefons Cerda, a Catalan engineer. As the city was devastated by epidemics,Cerda wanted to ensure that the new development would provide sufficient sunlight and ventilation for its residents. His plan was a large, grid-like district outside the old walls called Eixample (meaning "expansion"). The octagonal blocks were surrounded by streets that broadened at every intersection for greater visibility and better ventilation. It is particularly noteworthy that the design made traffic easy. It was Cerda that coined the word "urbanisation".