A simple tax system would be far more transparent and targeted than the current regulatory maze. Today, many builders negotiate our system by hiring expensive lawyers and lobbyists and buying political influence. It would be far better for them to just write a check to the rest of us. Allowing more building doesn’t have to be a windfall for developers; sensible, straightforward regulations can make new development good for the neighborhood and the city.

Second, historic preservation should be limited and well defined. Landmarking a masterpiece like the Flatiron Building or the old Penn Station is sensible. Preserving a post-war glazed-brick building is absurd. But where do you draw the line between those two extremes? My own preference is that, in a city like New York, the Landmarks Preservation Commission should have a fixed number of buildings, perhaps 5,000, that it may protect. The commission can change its chosen architectural gems, but it needs to do so slowly. It shouldn’t be able to change its rules overnight to stop construction in some previously unprotected area. If the commission wants to preserve a whole district, then let it spread its 5,000-building mandate across the area. Perhaps 5,000 buildings are too few; but without some sort of limit, any regulatory agency will constantly try to increase its scope. The problem gets thornier in places like Paris, practically all of which is beloved worldwide. In such cases, the key is to find some sizable area, reasonably close to the city center, that can be used for ultra-dense development. Ideally, this space would be near enough to let its residents enjoy walking to the beautiful streets of the older city.

Finally, individual neighborhoods should have more power to protect their special character. Some blocks might want to exclude bars. Others might want to encourage them. Rather than regulate neighborhoods entirely from the top down, let individual neighborhoods enforce their own, limited rules that are adopted only with the approval of a large share of residents. In this way, ordinary citizens, rather than the planners in City Hall, would get a say over what happens around them.

Great cities are not static—they constantly change, and they take the world along with them. When New York and Chicago and Paris experienced great spurts of creativity and growth, they reshaped themselves to provide new structures that could house new talent and new ideas. Cities can’t force change with new buildings—as the Rust Belt’s experience clearly shows. But if change is already happening, new building can speed the process along.

Yet many of the world’s old and new cities have increasingly arrayed rules that prevent construction that would accommodate higher densities. Sometimes these rules have a good justification, such as preserving truly important works of architecture. Sometimes, they are mindless NIMBYism or a misguided attempt at stopping urban growth. In all cases, restricting construction ties cities to their past and limits the possibilities for their future. If cities can’t build up, then they will build out. If building in a city is frozen, then growth will happen somewhere else.