Since 1973, Rosedale, a fine federal farmhouse, has basked in the sun atop a gentle hill, surveying a gradually diminishing domain. Rosedale's history tells a great deal about what should and shouldn't happen to land, houses and people in the Capital City.

Rosedale's 10-acre block in the heart of Cleveland Park holds many important stories. Community Wars of the Roses have been fought over property rights here. New houses going up on the site are examples of the new problems with solar rights, the search for a secure place in the sun. And above all, up on the hill is Rosedale, a reminder to save grandmother's house.

Three new three-story detached townhouses, designed by architects Wilkes & Faulkner, are well under way on 36th Street NW. They are true townhouses - not rowhouses - but vertical, formal, urban houses, facing the street and its problems head on.

They are designed by Winthrep Faulkner, well-known for his contemporary residential architecture in this city and this block. His grandfather, Avery Coonley, bought Rosedale in 1920 from the descendants of its builder, Gen. Uriah Forrest, friend and host to George Washington.

Rosedale, sitting on 998 acres, was very much a house of its time. The long gallery with its brick floor faced due south. The gallery roof offered protection against the summer sun and provided a sheltered place to catch the breezes. Trees to the north cut the winter breeze and freeze. Open lawn to the south let the light in.

To the west of Rosedale, on 36th Street, is a later house, also very much a house of its time. In 1937, Waldron Faulkner, father of Winthrop and son-in-law to the Coonleys, built a high-art-moderne house. The house presents a pristine symmetry to the street, not a leaf of its guardian trees out of place. Even today the house looks modern, and appropriately so. It basks on an acre and a half of land.

In 1969, Rosedale's manor house and seven acres were bought by the National Cathedral School for Girls. Despite protests from the neighbors, dormitories were builtbehind. The buildings were designed by Waldron Faulkner's old firm with another son, Avery Faulkner, (the firm is now Faulkner, Frye and Vanderpool.) The controversy caused them to be built rather close to Rosedale manor house, but at least the house's view and the street's view of Rosedale were preserved.

In 1963 and 1968, Winthrop Faulkner built expansive houses for his own family - the first one when they had three children, the second when they had five. The large glass areas and honest '60s contemporary design won them awards.

The Winthrop Faulkners now plan to live in one of the three new houses being built, their third, their family's fifth house on the block.

And these houses too, are very much houses of their time, the late '70s. In this they contrast strongly with the fake federal-front, "three-F" houses now being built on too many of Washington's empty spaces. So many wonderful opportunities have been lost in the city. Consider the Henderson castle on 16th Street NW, where the name (why not Castle Court or Henderson Houses instead of going out of town for a name like Beekman Place), the history and the view all have been lost.

Where splendid contemporary houses with glass walls to the sunny south (with a superb view of the city) could have been built, we have a mass of fake shutters and meaningless federal frills. But this is just one of the prevailing patterns of pastiche. We We tear down fine old houses of their period to replace them woth less solidly built imitations.

Faulkner has made no such error. His three new houses are geometric cubes, in what passes for high-1977 style. But they also answer concrete concerns of the day. Each house has a bank of sloar collectors, carefully set at a 60-degree angle in a mansard roof. The houses are sited so none of the three will shadow the other.

There are virtually no windows on the north side of the house, both to protect against the north wind and to provide privacy. The decks on the east side have awnings (a shading device too often forgotten) which will add a bit of color to the painted-brick houses as well as shade the second-floor decks.

The half-acre, triangular site has been laid out by Faulkner, with help from landscape architect Lester Collins, so each house has about the same square footage of land, but a section has been saved in back for a community swimming pool and fenced-in garden.

Probably the most handsome aspect of the houses is the seven-foot-high brick fence, so called because it is built of piers and four-inch walls. The wall gives each house a courtyard, private from the street. In the rear, a part of this wall is replaced by wrought iron to give a view of Rosedale.

Pear trees will peep over the brick fence at intervals. And tall weeping trees will shadow the east sun. Richard Cimermanis, the contractor, has accomplished some savings by building all three houses at one time, bringing the cost for the houses' 3,600 square feet plus basement to an economical $20 a square foot.

The houses are certainly not Rosedale, nor do they have 998-acre lawns. But they are good houses on good lots for their day. And what more can you ask of architecture?