Developer Billingsley lands huge Allen development site Prime corner at U.S. 75 and Rayburn Tollway is planned for $1 billion in development. The 238-acre property is zoned for mixed-use development in Allen. This artist's rendering shows an earlier plan for the site Billingsley just bought.(Contributed / Howard Hughes Corp.) 3:03 PM on Jun 1, 2021 CDT One of North Texas’ best-known and most successful developers has landed what has to be the prime development site along U.S. Highway 75. Billingsley Co. has bought the 238-acre southwest corner of U.S. 75 and State Highway 121 in Allen. The vacant tract was sold by Houston-based Howard Hughes Corp., which had planned a $1 billion mixed-use project called Monarch City for the site.