When you get up into the tower, keep an eye out for levers to open the gates (some are on the ground, some are on ledges you need to jump up to). As you climb up the tower, you will eventually get to 4 dragon statues with pressure plates that need to be activated to open a gate. After that the path splits; keep left to spiral upwards to where you can find a skeleton blacksmith and Lovis' loot, or right to go down a bit to another ladder down to a small platform where you can jump down to the section that contains the door to Lovis' chamber.