I am an architect and I certainly consider myself an environmentalist, but it appears to me that in a lot of cities, these new glass towers don’t add much at all to the city in terms of energy efficiency or quality of life. Often they don’t add many more housing units than the buildings they replace. I am also a heritage activist, not because I particularly love old buildings, but because there is so much to learn from them and from the neighbourhoods. and cities that were designed before cars or electricity or thermostats, and were built at surprisingly high urban densities.There is no question that high urban densities are important, but the question is how high, and in what form. There is what I have called the Goldilocks density: dense enough to support vibrant main streets with retail and services for local needs, but not too high that people can’t take the stairs in a pinch. Dense enough to support bike and transit infrastructure, but not so dense to need subways and huge underground parking garages. Dense enough to build a sense of community, but not so dense as to have everyone slip into anonymity.