 The rest of the tunnel was a result of the urban renewal of the late 1960s and early 1970s as designed by I. M. Pei, with major construction between 1972 and 1974.The tunnels were a vibrant part of the OKC landscape, including several shops and restaurants, but lost much of its popularity with the end of the last oil boom.Originally named the Conncourse, in honor of Oklahoma City banker Jack Conn, it was renamed the Underground after an extensive facelift conducted by architect Rand Elliott.