This seems to be a good place for a Wherigo cache as there are interesting sites in the area to visit. The posted coords will take you to convenient parking and the Sixth Floor Museum if you would like to explore the fateful events of November 22, 1963 in greater detail. This Wherigo is focused on outdoor locations and information not only related to the assassination of President Kennedy but also related to the roots and development of the city of Dallas.
The Wherigo cartridge contains several stages that are all within short, easy walking distances of one another. At each site you should be able to spot an informational plaque that will contain the answer to a question asked in the cartridge before the next stage is unlocked. As this plaza contains Elm, Main and Commerce Streets, you will need to cross the roads and I would strongly encourage you to take advantage of the crosswalks at the traffic lights as there is significant traffic through this area at times.
This is my first Wherigo and admitedly it is very basic. I've tested it and it appears to work fine, but I welcome all feedback as this has been a learning process in developing a Wherigo cartridge.