It seems only yesterday that Tysons Corner was just the sleepy intersection of Routes 7 and 123 in Fairfax County and cows were grazing on what now is the Westgate/Westpark industrial park.

Legend has it that a man named Tyson once has a small general store on the intersection whose name now rings big bells in the world of business and real estate development. In the past dozen years years a phalanx of shopping, business, commerce and residential development has emerged within and around the triangle formed by the Beltway, Leesburg Pike and Dolley Madison Boulevard. Altogether more than 1,000 acres are involved in the strategic Tysons area between McLean and Vienna, Va.

Now dominant on the Tysons skylind are the mall shopping complex created by T.N. Lerner, the well-under-way Rotonda complex of high-rise condominiums, the sentinel NADA (National Automobile Dealers Association) building near Route 7, a Holiday Inn, the 14-story Donimion National Bank building, the boxlike Honeywell building, an impressive Clarendon Bank and Trust building and the Regency Club condominium.

Some 600 acres have also been under intensive development as a research-development-oriented in dustrial park since 1962. This campus-like part of Tysons is known simply as Westgate/Westpark and its profile is less than overwhelming.

It began when Gerald T. Halpin and Rudolph G. Seeley decided to buy land from farmers and other owners for an assemblage that now totals about 600 acres. One of the key pieces was the 200-acre Ulfelder farm, which was begun by that family in 1925.

Fairfax County tax receipt show that Ethel M. Ulfelder of McLean once paid $831 in taxes on three parcels totalling 212 acres. But that was 1932, when her architecturally resplendent, 1870-vintage Maplewood house was a significant part of the totalling landscape around Tysons Corner.

The old mansion, which finally showed its age, was rared in 1970 after serving as the headquarters for the Westgate Corp. The corporation was formed in the early 1960s to develop the land on both sides Route 123. In 1970, Westpark Associates, a general partnership, was formed to develop Westpark, a 300 acre area north of the Beltway bounded by Route 123 on the east and the Dulles airport road on the north.

Halpin, who had previously been active in developming new properties for Atlantic Research, teamed up with Seeley, a business man who had married a member of the Ulfelder family. Halpin serves as president of the Westgate and Seeley as executive vice president and chairman of the board. They are also general partner in Westpark along with Charles B. Ewing Jr., an engineer who is a vice president of Westgate, and Thomas F. Nicholson, a realty professional who is vice president and treasurer of Westgate.

The Westpark general partnership includes Plicom Investments, Inc., a corporation formed by Peoples Life Insurance Co. of Washington and Commonwealth Life Insurance Co. of Louisville to participate jointly in Westpark while also providing a loan of $5 million.

After Fairfax County devised a master plan for Tysons Corner (with input from major landowners, Halpin recalled), the development of Westgate was undertaken by the Halpin-Seeley-Ewing-Nicholson team that now also includes Kathrym A. MacLane as vice president and secretary, Joan Bowe, C.B. Hammerle and Robert A. Potts as vice presidents and Elizabeth M. Sampson as assistant secretary. All hold some interest in Westgate developments.

Much of the development work of what now is 35 buildings with nearly 3 million square feet of office-related space is handled by Management Associates, Inc., in which, Halpin, Seeley, Ewing and Nicholson are active.

Most of the 36 buildings were built and leased by Westgate/Westpark, which has kept remarkably in tune with the charging patterns of realty markets. Outsiders credit the developers with an almost uncanny ability to keep building and bring in new tenants without making a big noise or having space go begging for long periods.

Occupied space averages more than $3 a square foot and space in new buildings scheduled to be finished in 1978 and 1979 will bring about $10 a foot.

Five of the buildings have been occupied by firms orgroups that have purchased sites from Westgate/Westpark. These include Honeywell, the National Machine Tool Builders Association, the Brick Institute. Flow General and Geico.

Major tenants, among a total of about 50, include Mitre, Planning Research Corp. and TRW. Since the contemporary Commons complex of 578 dwellings was built in the 1860s, occupancy has been near the 100 per cent level, according to Westgate people.

Gordon H. Marks, who works closely with the Halpin-Seeley team, said that everything completed is leased and that some tenants expand and others voluntarily seek space there.

Halpin, nothing that many of the new tenants in Westgate/Westpark have been business and commercial enterprises, said he He sees a diminishing role of Defense and Defense-related contracts, which originally formed the backbone of the office park complex. He added that jobs generated within the total Tysons complex now total more than 12,000 and said the number will likely hit 13,000 next year.