Pete and I went to Castle Island and took the tour of Fort Independence. We were rewarded with cool views of the city skyline and the harbor islands from up on the ramparts. If you're a local, you can head out there on Thursday nights when they open up the Fort and you can walk the ramparts on your own. The cool part of Castle Island is that you can hang out on the beach, lounge on the grass and watch planes take off from Logan, go fishing off the fish pier, or (if your timing is right) watch the cargo ships unload at the port next door - usually containers or shiny new cars.
Click on the photo to enlarge!