JAMES and Alice Clarke's contemporary castle rises from its point of land, jutting out into the Miles River in the Eastern Shore, stark, sturdy and strong against the buffetting of wind, water and time.

"As long as the North American continent stays above the water, this house will stand," said John Henry Sullivan, its architect.

No one could say he is wrong. The house is built to defend all the pleasures of this hour of time, in trust for the next millenium. Nothing in the house will ever have to be painted.

The materials are ageless: precast concrete. Vermont slate roof glass, hardwoods, all carefully selected to blend with the colors of sky and river, and to last forever with little maintence.

The site is the stuff of watercolor paintings. But it is no still life. Something is always happening to change the scene. Five thousand ducks may suddenly settle on the shore. At another time, the wind will whip the water into mountains and valleys of foam. The trees make black branch sculptures in winter and festivals of flowers in the summer. Above all, the light, reflected in the miles of water from the dome-shaped sky, colors and fades in a palette of watercolors.

The house is a totally contemporary design with no gimcracks or geegaws dredged up from another period. It could only have been built in the late 1970s.

Without any doubt, no matter how you feel about the house, it is one of a handful of major private homes built in this area in our time. For the architect and for the owner, who was also the builder, the house is the masterpiece of a lifetime, the culmination of all they had learned in a quarter of a century or so of building. They were schoolboys together, and the house was in some ways a boyhood dream come true. Both Clarke and Sullivan said separately, "We could never do it again." Both are very proud they did it once.

It stands on a flat piece of land, just above the river, not on a high bluff. It is built of concrete and not stone. Still, the house is in the tradition of German Rhine River castles, planned to command a position and to sand against onslaughts.

"Before it was finished," said sullivan, "people used to come by boat to look at it and ask if we were building a fortress. When the panels went up, people asked, 'is it Stonehenge?" The 40-foot-long concrete beams, coming across the Bay Bridge, also attracted a lot of attention.

Every detail is worked out to a centimeter. "The house is designed and built with such careful attention, Jimmy can sink down in his chair and look without seeing any rough spot to offend his professional eye," said Sullivan.

A house like this is an exhausting task -- both in effort and money. To design the house took two years. The actual builder took better than a year and a half. The concrete panel system alone involved 100 drawings. Each room is as exhaustively designed as are most people's entire houses.

The concrete panels are used for all major wall surfaces. Five miles of low voltage wiring makes it possible to command all the house's complicated electrical security and lighting from every room.

The floors are Pennyslvania bluestone slate, framing areas of cherry, walnut and pine flooring. The ceilings are all wood, matching the flooring. The doors are teak, made to order to Washington Woodworking.

The ceilings and the floor level vary not only from room to room but within rooms. Every vista is unexpected. Sometimes, as in the living room, the ceiling soars to 20 feet or more. In the cozy sections such as the den, it comes down to 8.

On the river side, the house is almost all glass, opening out to the view, in contrast to the road side.

Precast concrete is not a common residential building material. The owner owns HRW, a Bladensburg precast-concrete firm, so he knew the remarkable possibilities of the systems.

"Mrs. Clarke worried for fear the concrete would be cold," said Sullivan, "but it isn't if you do it right. I think these panels are some of the best in the world. The cement is a warm color, brought in from Pennsylvania.

"The concrete is board formed -- rough sawn redwood was used to make the forms." The concrete panels are acturally pressed against the rewood so they become a negative of the rough redwood. You even see the impression of the nails in the forms. This texture adds surface intrest to the walls. And of course, this being 1980, the walls ar super insulated to keep them from feeling cold.

From th back country road, we drove into the 16-acre estate, not long ago. The road winds and twists and turns, according to a design by landscape architect Miles Riggle. He also scooped and shaped the land so it would undulate softly, and plated trees and bushes to hold the land, delight the eye, and moderate the climate.

Finially we saw the house and caught our breath. The towers from which spring the chimneys and skylights rise on the four sides of the Vermont slate hip roof. A great window composed of triangles points to the entry, at the end of a long covered portico, leading from the parking area. From the entry court, the house seems closed and private, reserving its warmth and friendliness for the interior.

To one side are the tennis court and the swimming pool.

The entry hall establishes the house's easy monumentality. Against the board-textured concrete panels is a painting of a nude back. Below it is a table, a cermonial table if you will, designed by Alessandro especially for this house, a commission from Cynthia Reed of Daly and Reed, the interior designers who worked on the house. The table is a beige color to complement the walls covering. Alessandro says the table is a faux slate finish. The table is two semi-circles reversed.

"Cynthia and I went around with hunks of concrete in our pocket to match against furniture," said Alice clarke.

From the foyer, the vistor goes left to the atrium, the family goes right to the kitchen.

The astrium is as big as some people's houses -- 24-by-24 feet. The ceiling, 20 feet above, is all skylights framed by big heavy beams. Its proportions reveal the house's module -- 4-feet square. The room is designed to hold a collection of art -- preferably art in which color and texture are important. The Clarkes have commissioned a large tapestry from Leroy Wilce, a weaver in Arizona. Sullivan, who collects quilts, would like to see Amish quilts hanging from the walls.

A 5-foot-wide balcony goes around the upper level and leads to three bedrooms, each with its own deck and heating system. "If you stayed in a different bedroom each time, you'd feel as though you'd been someplace quite different," said Sullivan. "The views from each are so different." beside the staircase is an area covered with gravel to hold plants.

At the other end of the atrium, the double-sized openings goes to the dinning room. Here a slightly boat-shaped travertine table top rests on another block of travertine, all to a design by Clarke. The sideboard also is topped with travertine. The floor is Pennsylvania blueslate.

Alice Clarke loves to cook. The brick-floored kitchen is open to the dining area. One section, by a window wall facing the bay, serves for family dining. The working part is organized in a series of counters forming a square, with a metal rack above for handsome pots and pans. Two sinks and two cooking units are set into separate counters. A freezer and refrigerator are built into the kitchen side of the pantry wall. The pantry is a separate room, an important one if you're that far from the supermarket. Of course during crab season they do well from their allotted two crab pots.

Alice Clarke's desk and cookbooks are at one end of the family dining area. Beyond is the greenhouse with its angled glass walls and above it an arched glass roof. The two-car garage backs up to the greenhouse.

On its roof are 154-by-8-foot solar pannels. The solar heat is intended to warm the swimming pool, the domestic hot water and to help with the floor radiant heat. The house has three complete heating systems: the floor radiant heat, the hot-air furnace and individual heat pumps for the upstairs bedrooms.

On the opposite side of the atrium is a small, book-lined den/gun room, with Clarke's hunting guns in a glass case. On a wall, over the firplace, is an Andrew Wyeth painting, discovered for the Clarkes by Sullivan. The painting shows a tree and landscape that very well could have been (but wasn't) painted on the premises. Alessandro's "rotunda" side table with a lizard finish also was especially commissioned for this spot.

Around the corner is a bar, complete with a draft beer tap. A sitting area is adjacent. The door to a large screened porch is near here.

And then you step down into the sunken living room with its soft comfortable seating and generous fireplace, one of six in the house. At one end is a card table and chairs and some handsome chests. At the other, on the higher dining level is a Steinway piano, chosen by the Clarkes' sons, Paul and Buddy. Paul is an architect, now studying whales in Puerto Rico. Buddy is a jazz musician. The Clarkes' daughter is a Catholic University law school student.

The floors, both in the living room and the music area are covered with Oriental rugs.

The master bedroom suite is most elaborate. A king-size bed has its own built-in headboard, made to order, as were most of the cabinets in the house, by Washington Woodworking. A comfortable fireplace is on one wall. A step down section with deep windows and easy chairs seems to be perfect for reading. Behind the bed are two dressing areas, with specific places for everything, all carefully designed by Alice Clarke.

Her bath is a marvel. The sunken tub looks out onto a small glass roofed viewing garden. James Clarke's sauna has a wall of glass onto the garden as well. He has a curving tile shower, and beyond, an exercise room with all the equipment, and a view of the swimming pool.

James and Alice Clarke's house is a very personal house, with every detail the choice of people who have thought long and hard about what they like. Its lessons however, of honest, sturdy materials, and module designs are worthy of note for houses far less elaborate or costly.