The Merizo Bell Tower is a squat limestone structure standing a short walk from the church, built around 1810 during the Spanish colonial period. It is one of only two remaining Spanish bell towers on Guam, the other being at nearby Umatac, and is listed on the US National Register of Historic Places.
The tower's construction — thick volcanic limestone blocks in a simple, solid form — reflects the pragmatic building style of the Spanish missions in the Pacific. It has survived multiple typhoons and the destruction of World War II largely intact, a rare piece of tangible Spanish colonial heritage in Micronesia. The bell is no longer in place, but the tower itself is well preserved and stands in a small park within easy walking distance of the church.