The Cambridge Planning Board last night recommended that the Harvard property on Observatory Hill be down-zoned to limit the heights of any buildings the University might build there in the future.

The recommendation, which will be sent to the city council some time next week, will request that the Harvard-owned land bordered by Garden, James, and Mason streets be down-zoned to have the maximum height of any buildings from 85 to 35 feet. The city council is the only governing body which can make a change in the zoning map, and the proposed change from a C-1 to a C-2 classificationmuy be approved by seven of the nine councilors.

A petition submitted to the city council from the residents of Observatory Hill two weeks ago requested that the Harvard property be down-zoned to a residential B classification, leaving the University will less than one seventh of the building space it presently has available.

Radcliffe's proposed athletic facility on Observatory Hill originally prompted the Cambridge community to request a down-zoning this summer, when protests turned away from Radcliffe's project to focus on Harvard's long-range plans. The plans published in 1975 designate some of that land as a possible site for a parking garage although Harvard has no present plans to build a garage there.

Members of the planning board said last night they did not favor down-zoning the property to a residential B classification because the move would not severely limit Harvard's building space, nor meet the community's goals to halt construction of the athletic facility.

"I really don't see down-zoning as the answer to anything," Arthur C. Parris, chairman of the planning board, said, adding that Harvard could still build anything it wanted on its property.

The proposed building design for athletic facility fits the requirements of all three zoning classifications under discussion, and a change in the zoning map might only delay the granting of a building permit.

Paul E. Dietrich, a member of the planning board, said last night the city council will probably favor a change in the zoning map.