An illustration of Jane Jacobs' point about the value of "a large stock of old buildings" to center city health

In Death and Life of Great Cities, the author lists four factors that undergird healthy cities.  One is "a large stock of old buildings."

The interior of a second-floor office space in 123 S. Broad St, occupied by the architecture firm Coscia Moos.

The point wasn't that these buildings are attractive (hopefully) and support historic preservation, it's that "old buildings" are paid off and offer lower rents, and therefore support innovative uses like business startups that need low costs in order to develop ("Jane Jacobs and the value of older, smaller buildings," Journal of the American Planning Association, 2016, "Big Data Backs Jane Jacobs: Cities Need Old Buildings," Smart Cities Dive).

Of course, she wrote that 60+ years ago.  

In a city like Washington, where the height limit constrains development, old buildings tend to get torn down and rebuilt or renovated so that they can continue to command higher rents.  

That's why I argue DC should allow higher heights, because small organizations are displaced to the suburbs, reducing the economic vitality at the core (although this is mostly a theoretical argument).

-- "Another attempt to raise discussion about the DC Height Limit"

In Philadelphia, 123 S. Broad Street, an old building not paid off, but with lower financing and running costs, is able to thrive by renting to organizations attracted to historic architecture, the ability to lease smaller spaces than typically available in newer buildings, and lower rents ("123 S. Broad is finding a niche in Philadelphia’s uncertain office market," Philadelphia Inquirer).