The Galata Bridge is a bridge that connects the Karaköy with Eminönü. It is on the Golden Horn which is in the Bosphorus. Galata bridge can be opened when a big ship passes through.
When you want to go between Eminönü and Karaköy, you will need to use the Galata Bridge. You can take the tram to pass the other side but if you want to enjoy the bridge, walking is recommended. If you walk on the top of the bridge, you will see the local fisherman. It is a good point to fishing.
But if you are more interested to sit and enjoy longer, you should take the way under the bridge. There are lots of restaurants and bars under the bridge. Eating fish is very common in the Galata Bridge and they are usually fresh because the local fisherman catches the fish just near the restaurants. The other thing to do in the bridge is drinking the local alcoholic drink: rakı. Almost all of the places in the bridge sells rakı and most of the people goes there to drink rakı. It is actually quite a good place to drink it because of the amazing view of the Bosphorus Bridge and the smell of the sea.
When you walk through the bridge, you will see the staff of the restaurants will be very insistent about calling you. But make sure you find a place to sit you can see the view of Bosphorus Bridge.