Sendai Castle Ruins is the former site of Sendai Castle, now mostly known for its panoramic views over the city. Today, there isn’t much of the original castle remaining. The site mainly consists of an observation area, a shrine, and a small museum with a few displays, including samurai armor and a model of what the castle once looked like. It also tends to get pretty crowded with tour groups and visitors. Personally, I wouldn’t go out of my way to visit unless you have extra time in Sendai. If your schedule is tight, I think it’s easy to skip.