The Carleton Martello Tower is one of nine remaining Martello Towers (small defensive forts built by the British Empire) in Canada and a National Historic Site. This particular fortress was constructed during the War of 1812. Although it was completed after the War of 1812 in 1815, the Carleton Martello Tower served as a British defensive structure until World War II. Like other Martello Towers , this one is round with a flat roof once used to mount artillery.

Today, you can explore both the exterior and the interior of the tower, where you'll find a reconstruction of a 19th-century barrack room as well as information on Saint John's participation in the Second World War. While most visitors enjoyed this taste of military history, one TripAdvisor user claims that the Carleton Martello Tower is worth visiting for the views alone: "Picture-taking on a clear day is wonderful because the tower, obviously, overlooks the bay."

The Carleton Martello Tower sits south of downtown Saint John, a little over a mile from the Reversing Falls. Visitors are welcome to explore the tower every day between June and the first weekend of October from 10 a.m. to 5:30 p.m. (you can still visit during the winter, but you won't be allowed to enter). Admission is about $4 CAD ($4 USD) for adults, and there are discounts available for children and senior citizens. For more information, visit the tower's website.