right off the bat there is one we stole -- i should say they stole exactly from leonardo divinci. the way the walls are tows out at the base, distributes its grouped pressure over a much greater surface area so we don't sink into the marshy ground. once the castillo's built, over time they see that they have to go ahead and modify the way they are going to defend this area because we are on a finger of land surrounded on three sides by water. there is only one approach down from the north to go ahead and get to the city by land. you want to be able to defend the whole thing. the best way to do is that is encompass it with a fortification. but this took so much effort to build, the amount of effort would take to build a stone fortification around the whole city, st. augustine really wasn't worth it. so they built wooden fortifications. small outlying fortifications and also ultimately walls around the city itself. 14-foot walls with gun placements around the three sides of the city. right where we are now is pretty much where about the last five fortifications were built. from here