Any object that's at the "top of a tower" has gravitational potential energy.
The bell does not "weigh" 60 kg.
"kg" is an abbreviation for "kilogram" ... a unit of mass, not weight or force.
I'll assume that "60 kg" is the mass of the bell, and now I'll go ahead and solve the problem that I just invented:
The gravitational potential energy of any object is
PE = (gravity acceleration)·(object's mass)·(height above somewhere)
-- The acceleration of gravity on Earth is 9.8 m/s²
-- The object's mass is 60 kg
-- Use the "height" above the ground, just like the height of the tower.
PE = (9.8 m/s²)·(60 kg)·(45m)
PE = 26,460 Joules
