Dense, compact cities are “the way forward in the development of man” and are critical in combating climate change and inequality, renowned architect Lord Richard Rogers told delegates at the recent ULI Europe conference in Paris.

Keynote speaker Rogers—speaking in the same city as the Pompidou Centre he designed with Renzo Piano, shooting him to fame in 1971—said that cities that “sprawl”—spreading out over large areas, thus creating a need for cars—need to be shunned, and dense cities that promote dynamism and collaboration need to be encouraged.

“The compact city, the city that has mixed living, working, and leisure, which is connected through transport and infrastructure, which has good public space and is well designed—these cities are already here,” said Rogers. “Some cities are doing it well, and some are doing it badly.

“We need to rediscover the classical order of things, where there was a mix of rich and poor. There are two problems tearing the world apart, and they are climate change and the gap between the rich and the poor. We need dense, mixed cities that open doors instead of close them.”

Download: Presentation by Richard Rogers | Presentation by Greg Clark

The comparison to which he returned several times was Barcelona in Spain and Atlanta in the United States, both of which have roughly the same population, but with Atlanta taking up 26.5 times as much space. “Atlanta has a huge problem with cars, and Barcelona has virtually no problem with cars,” Rogers said.

Comparing Los Angeles and Tokyo, he pointed out that in the former 80 percent of people travel to work by car, and in the latter 78 percent of people travel to work on public transport, and in Manhattan 45 percent of people walk to work.

He added that the Torre BBVA building he had recently designed in Mexico City—notorious for its traffic problems—incorporates a garage with space for 3,000 cars, while the similar-sized Leadenhall Building in the City of London, completed around the same time, has ten car parking spaces in total.

“One hundred years ago, the average age of someone in the city was 17, and the average age of someone in the country was 34—you died younger in the city, so of course people wanted to move to the country, and that is how the suburbs grew up,” said Rogers. “But today those trends are being reversed.”

He argued that cities should be building “in, not out,” meaning that areas should be made denser rather than spreading out, and that this does not inevitably lead to the building of more high-rise towers.

“In London, we have a policy of ‘brownfield first’—we have huge amounts of brownfield sites in England, and it isn’t acceptable that someone should have to travel 30 miles or more to get to work.

“London is made up of 32 boroughs, and around 600 hubs, most of them around public transport of some sort, where there are houses and a few shops. We think you can make these areas more dense, as there is already life there and you are not starting from scratch.”

He showed delegates plans of three designs for housing that use the same amount of land and deliver the same number of homes—one low rise, one mid rise, and one high rise—showing that towers are not the only solution to the problem.

He finished with a passionate plea. “When the citizens of Athens became a citizen, they had to swear an oath,” he said. “‘I shall leave the city more beautiful and greater than it was when I entered it.’ We need to ensure we do the same thing with our cities today.”

Another panel followed, echoing many of the points raised by Rogers.

“The relationship between density and innovation and economic performance is clearly shown in our studies,” said Greg Clark, professor and senior fellow at ULI. “Density is basically good for economies and good for societies.”

Hugues Parant, chief executive of EPADESA, the municipal body in charge of overseeing the development and extension of the La Défense district of Paris and its surrounding areas, said that he and his colleagues are trying to emulate areas like the City of London and Canary Wharf, which have brought vibrancy and life to previously soulless commercial areas.

“We are competing internationally—not just with Canary Wharf, but [with] places like Gangnam in Seoul,” he said. “You have to bring life to an area, but it is difficult to add to what is already there when you have regulations, which means you can’t block certain viewing corridors. So we are building around and behind La Défense, and connecting it by public transport.”

Jürgen Bruns-Berentelg, chief executive of the HafenCity redevelopment project in Hamburg, Germany, brought the conversation back to the dominant theme of the day—the large increase in migrants currently arriving in Europe from the Middle East, and the increased need for housing this would create.

“We are going to have 80,000 more people arrive in the city this year, and that is a tremendous issue in terms of stress on the city’s governance, supply of housing, and creation of an integrated labor market,” he said. “Yes, we need to increase density and increase the supply of housing, but it becomes a question of social justice and integration of a population for the city, and a question of social justice on a global scale.”

Lief Andersson, chairman and founder of Swedish developer Areim, also raised the fact that densification of cities has a strong political element.

“There has been a lack of political leadership in Stockholm and Sweden,” he said. “There is rising demand and little supply, but you need demand to rise in a sustainable way. The overall plan is done well, but individual issues make it difficult to implement this. There is always a conflict between beauty and density when it comes to listed buildings, for instance, which politicians don’t want to address.”

Mike Phillips is the editor of EuroProperty, the monthly magazine dedicated to European and U.K. cross-border property investment.