Lincolnshire Police are treating a fire at a former pub on Skellingthorpe Road as arson.
The incident happened at around 8pm on Thursday, May 25 at the former Monson Arms.
Emergency services attended the blaze, which saw traffic control in place for several hours.
The Monson Arms closed to the public in 2015 and has since been empty.
Lincolnshire Police are now treating the fire arson, however, at the time of writing it is unknown how the fire was started.
Police are also investigating a spate of arson attacks in the area.