Here I have made an exterior of the building and some of the surroundings of it, I used the box tool to create the concrete floor and gave it a concrete material and adjusted the noise of this. I then used the foliage and put in plants and tress to make my exterior look more effective and put in a sliding door again can be found in the geometry panel. I then adjusted the height, width and length of the door and also was tweeking the 'open' modifier to see how will it look like once animated.