PHOTOS: City and state officials gathered for a “solemn” day of remembrance Sunday, honoring the many fallen firefighters who have served the city of Boston at the 126th annual Memorial Service at the historic Forest Hills Cemetery in Jamaica Plain. “It’s a solemn day because you remember the firefighters who have lost their lives,” said Mayor Martin Walsh. The event, presented by the Charitable Association of the Boston Fire Department and the Veteran Fireman’s Association, took place at the Fireman’s Lot at Forest Hills Cemetery, which was founded in the early 1800s. For 126 years, all across the country, the second Sunday in June is set aside to remember fallen firefighters. Firefighters decorated graves at the lot with flowers and paid tribute to fallen comrades by singing “Amazing Grace,” and engaging in prayers. Walsh said he often thinks about the tragic 2014 Beacon Street fire that took the lives of two city firefighters, Michael Kennedy and Ed Walsh.