Preliminary design work began in the spring of 1964. During this phase the tower evolved thru four design concepts, the final being the design we see today. According to the Tower’s official guidebook the sprocket shape cross-section of the shaft offers the best durability against the elements while retaining the strength to withstand hurricane force winds. The top house is divided into four levels:
- The first level is a split level restaurant featuring a rotating dinning area on the lower level rotating at a rate of one revolution per hour. In high wind conditions the rotating floor is stationary. On the upper level towards the center are the kitchens and stair access to the lounge on the second level.
- The second level is a lounge featuring a seating area partly overhanging the open dinning level below. The lounge uses approx a third of the space on this level and is located to on the northwest side taking full advantage of the dinning areas two story windows and the breathtaking view of downtown San Antonio below.
- The third level is the main observation deck which features an enclosed viewing area near the center as well as an open air viewing area along the edge. During the latest renovation some of the space near the center was enclosed to create two small banquet rooms.
- The fourth level originally was an open air observation deck, however, this level was closed to the general public some years after the fair due to a small handful of people scaling the metal railing and jumping off the roof.