Police are appealing for information after a bench was set on fire on the River Walk in Grantham on Saturday, May 31 at around 7.30pm.
A fire crew from Grantham was called to the area and extinguished the flames using a water backpack.
The bench was located between Wyndham Park and Grantham College along the river, and the fire is thought to have been started deliberately.
Nobody was injured in the incident.
Officers have asked for anyone who may have witnessed the incident, or seen or heard anything suspicious in the area around the time, to contact Lincolnshire Police on 101 quoting incident 437 of May 31.
Alternatively contact the independent charity Crimestoppers anonymously on 0800 555 111.