The Conservation District seems to have united two diametrically opposed forces--property owners' desire for development and the community's resistance to change.

"The Historic Commission has done a good job of working with all the constituencies," Nathans says.

While the differences between a historic and a conservation district are small, they were significant enough to win over the Council--and the property-owners in the Square. Minor building changes can be approved by the director of the Historical Commission--no lengthy process is necessary. And the power of the HSDF as a third-party group is ambiguous in the city ordinance rather than guaranteed.

Finally, an extra gift was given to property owners in the form of an amendment to the Conservation District legislation.

Tonight's City Council meeting will decide whether to significantly downzone much of Cambridge--a prospect which might have greatly reduced Harvard Square development options.

However, property-owners in the Square can rest easy.

With the formation of the Conservation District, the ratio of floor area to potential building square footage for the Square has been frozen at a minimum of three. In other words, even if the Square is downzoned, the ratio will not be reduced below this limit.