When Peter Palumbo, a British developer and devotee of fine architecture, acquired the famed Mies van der Rohe-designed Farnsworth House in Plano in 1972, he liked the countryside around the small farming town so much that he began buying up adjacent tracts.

In recent years, his stranglehold on local property has kept other developers at bay. As subdivisions spread west from the Fox Valley, Plano remained an island of bucolic serenity.

Now, Lord Palumbo, who has opened Farnsworth to the public while his visits to the area have become less frequent, is preparing most of his land for development. A company controlled by a family trust, City Acre Investment Trust Ltd., is ...