Ok Jaeger, to give some feedback on these two build: the main one would be to blockmix your builds. This means that you use different blocks within the same surface in order to make it look more interesting, unlike what you have done now with only using one kind of block. Blockmix can add depth to your builds without necessarily using more than 1 block layer and makes it look more interesting. Another aspect that can help with making your build look more interesting is adding a gradient, this makes your builds seem more weathered by the environment and creates a more realistic look. This bit of feedback would predominantly be applicable to your tower.
View attachment 26794
I have included this photo of one of my own builds so you can see how using a blockmix and a gradient can help with your builds. You can probably see that the blocks transition from dark to light grey: this is the gradient. You probably also noticed that I used several kinds of similar coloured blocks within the different shades and thus made it more interesting to look at. Employing these techniques in your builds will improve them quite a bit, though you may have to mess around with it first to get the hang of it and be sure you got a good one.
Now as to your bridge build: the tips I have given you above also apply there, but a few other things also can help with improving it. The transition from the sandstone to the red cobblestone is quite abrupt, so either make a kind of transition from the sandstone to the cobblestone by using a gradients/blockmix or (if you want to follow the real life inspiration more) add a barried of border between the two layers. Also try to add a blockmix to the terrain and the river bed and add some vegetation to it. If you look at more up to date parts of the server, so the rivers in Anorien or the updated part of the Anduin and just terrain in general, you will see we very rarely use only one block in it, just as in our buildings. The vegetation will also help give a more natural look to your rivers and make them come more alive. As to the arch of the bridge, try to make it a bit more rounder. I can see you have used the sandstone archway blocks, but those don't really lend themselves well to an arch bigger than 3 blocks wide, so you best use our older technique of using blocks, stair, slabs and half slabs here. You can find examples of this in severasl bridges on mainworld and well as on the photo I posted above, where the gateway uses this technique.
I hope this feedback helps you in further developing your build skills!
