Originally built by Leonard's Department store in 1962, the Tandy Corporation purchased the department store, its parking lots, and the subway in 1967. The corporation built its headquarters, the Tandy Center, on the site in 1974. Although it demolished the original store, Tandy retained the subway.
After the closure, one of the streetcars used on the subway was acquired by Dallas's McKinney Avenue Transit Authority, who modified it to again make it suitable for in-street use, and it operated in service on the McKinney Avenue heritage streetcar line in Dallas until the mid-to late 2000s. As of 2012, it remained in storage in Dallas, out of use.
In April 1982, the first PCC streetcar to run the line in 1963, "Leonard's Number 1", was saved from the cutting torch by a Tandy computer programmer and stored on a farm south of Fort Worth, where it remained for over 25 years. It was donated to the Leonard's Museum in 2007. On February 2, 2008, it was moved to a restoration location near Benbrook, Texas. Leonard's number one is now on public display in the lobby of Texas Capital Bank, Fort Worth (One City Place).
Below is a link to an excellent summary of the Tandy Center Subway's history as provided by Professor Jon Bell. Includes excellent photos: