Answer:
I am a protector. I sit on a bridge. One person can see right through me while others wonder what I hide.
small land in water.
I'm an animal. I love marching. I always wear a tuxedo. What am I?
Without a bridle or a saddle across a thing I ride a-straddle. And those I ride by help of me though almost blind are made to see.
I have cities with no people, forests with no trees, and oceans with no water. What am I?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.