Harvard and the Cambridge Historical Commission appear to have reached an agreement over the status of two buildings that currently house the Harvard University Police Department (HUPD) and the Registrar's Office.

Affected are 20 and 29 Garden St. Harvard originally opposed a proposed expansion of the Old Cambridge Historic District that would have included the structures on both sites. Buildings in historic districts cannot be altered without the commission's approval.

Under the compromise, the new Arsenal Square extension of the historical district will include 20 Garden St., which contains the Registrar's Office. It will not include 29 Garden St., as the commission originally proposed.

Instead, Harvard has agreed that it will not alter the exterior of 29 Garden St.-Which houses graduate students and HUPD and once served as a first-year dormitory--without first consulting the commission.

Still unresolved, however, is the festering issue that originally prompted the proposed extension of the historic district--the plans of the owners of the Sheraton Commander Hotel to demolish three historic houses to build a parking lot.

Walter A. and Edward N. Guleserian, the owners of the hotel, proposed in January to demolish the houses. In response, the commission declared them to be of historic value. The owners responded by filing an appeal in Middlesex Superior Court. That litigation is still pending.

Harvard planning and Real Estate Associate Vice President Kathy A. Spiegelman proposed the bargain in a September 21 letter.

The commission approved the deal with Harvard on October 19, but remains in a deadlock with the Guleserians.

The commission has agreed to allow the partial demolition of the rear wings of the three houses, but the sticking point is the hotel owners' insistence on the total demolition of 24 Garden St. which is situated between the other two structures.

The commission's final report, released Friday, leaves the late of that house on doubt.

"It doesn't preclude them from asking" for its demolition, said Charles M. Sullivan, executive director of the commission.

But it is unlikely that the commission would give permission for that to happen.

Efforts to reach the Guleserians last night were unsuccessful.