David B. Brownlee and George Claflen are vice chairs of the Design Advocacy Group of Philadelphia

We all thought Jewelers Row was safe.

Until the announcement that Toll Brothers planned to demolish four buildings and replace them with a high-rise, almost all Philadelphians believed that this fondly regarded piece of our city was protected by law. We thought, surely its small-scale business bustle is safeguarded by appropriate zoning, and its quaint charm must have earned it protective historic designation.

We were wrong.

The Central District Plan, which was written in 2013 as part of Philadelphia 2035, our impressive new comprehensive blueprint for the city, recommended "down-zoning" this stretch of Sansom Street and a swath of other smaller buildings in this area in order to "right size development to better transition from high-rise Market Street to [the] rowhouse neighborhood" of Washington Square West to the south.

However, our leaders did not have the political will to act on this sensible recommendation and take these tempting real estate morsels off the plates of developers. Right now, the four-story houses of Jewelers Row are zoned CMX-5 (Center City Commercial and Residential Mixed-Use 5) - which allows the tallest, densest development in the city.

The historical charm of these buildings is similarly unprotected. Although Jewelers Row was designated as part of the East Center City Commercial Historic District in 1984, which placed it on the National Register of Historic Places, this does nothing to keep it from being destroyed. Unless a property owner has taken advantage of federal tax benefits while restoring a building on the National Register (and the owners of these buildings have not done so), the building can be altered or even demolished. Protection only comes with listing on the Philadelphia Register of Historic Places, and Jewelers Row is not enrolled there.

That leaves us with only our passion, good sense, and strong voices to preserve and protect the rich urban ecology of small businesses and historic buildings that is Jewelers Row. And so Design Advocacy Group (DAG) joins those who are passionately, sensibly, and loudly asking Toll Brothers to do the right thing, even if they don't have to: Preserve the historic facades, preserve the scale, and preserve the small-business vitality of this just-about-perfect part of Philadelphia.

But we also call on Mayor Kenney and his administration to reduce the chances of this happening again. As DAG stated in our "agenda" for the 2015 mayoral election, and as candidate Kenney promised, Philadelphia, America's first and only World Heritage City, must make a comprehensive inventory of our historic resources and create a strategic plan for them that is integrated with the rest of the city's planning apparatus.

We deserve to have the things that we care about protected, and we need to be fair to developers, too. They deserve to know in advance what we hold dear, and what we will fight to preserve.