The article suggests these towers are being built in blocks of lower buildings. Each block has a "allowable total square footage of building" limit. The develop

The article suggests these towers are being built in blocks of lower buildings. Each block has a "allowable total square footage of building" limit. The developers are buying lower buildings, or unused area rights for lower buildings, and conglomerating it into towers. It seems this is an improvement for sunlight and space at street level. Rather than the sidewalk being against a massive wall of 10 story buildings looming over the streets you can have more human scale buildings and open space and a single spire reaching up out of sight. The narrow shadow of the spire will swing around like a sundial during they day, but its shade will move on.