A 7.1414-acre tract of property was originally owned by Lincoln Property Co. No. 38. On September 15, 1977, Harvin Moore, as trustee, purchased the northern 2.7264 acres of the tract and obtained an option to purchase the southern 4.4150 acres. The north tract was conveyed to Corporate Plaza Company, a Texas joint venture owned by Harvin C. Moore, Jr., Tyler D. Todd, the Ben H. Powell Trust, and the Marian Powell Trust. Each partner owned 25% of the joint venture. In 1977, this joint venture built Corporate Plaza 1, a two-story, 50,000 square foot office building. On December 20, 1977, Lincoln conveyed the south tract to Harvin C. Moore, Trustee. On October 4, 1980, the south tract was conveyed to Corporate Plaza 2 Company, a Texas joint venture owned by Harvin C. Moore, Jr., Tyler D. Todd, and the Marian Powell Trust. Moore and Todd each owned 25% of this joint venture, and the Marian Powell Trust owned the remaining 50%. In 1980, Corporate Plaza 2 constructed a three-story, 100,000 square foot office building known as Corporate Plaza 2. A parking garage was built on the south side of the building because parking along the north side had been allocated to the Corporate Plaza 1 building. The main visitor entrance to Corporate Plaza 2 was near the entrance developed in connection with the construction of Corporate Plaza 1. When Corporate Plaza 2 was built, Corporate Plaza Company still owned Corporate Plaza 1. The properties were developed as part of a common plan and project. The buildings were viewed and intended as one economic unit, consisting of two phases and two buildings totaling 150,000 square feet, situated on approximately seven acres. For Corporate Plaza 2, the driveway, which was located between the two buildings on Corporate Plaza 1 property was widened. Visitors to either building could reach each of the buildings from any entrance to the 7.1414-acre tract. Use of the driveways by tenants and visitors of each building began immediately in 1980. On March 4, 1986, Travelers Insurance Company purchased Corporate Plaza 2 out of foreclosure. Hammerly Corporation purchased Corporate Plaza 2. Great-West Life Assurance purchased Corporate Plaza 1 out of foreclosure on March 7, 1989. Houston Bellaire purchased Corporate Plaza 1 on November 11, 1989. In October 1996, P began negotiations with the Hammerly to purchase Corporate Plaza 2. Hammerly asked D to execute a cross-easement between the north and south properties allowing the use of the curbcuts, parking lots, and driveways. D declined and indicated that it had plans to build a wall between the properties. P purchased Corporate Plaza 2 on March 5, 1997. D offered a lease to TCP but no deal was reached. D started to build the fence between the properties. P sued seeking a declaration that it was entitled to an easement by estoppel, implication, prescription, and necessity. The trial court granted P an easement by implication. D appealed.