Complex sentence: In 1369, lightning struck the top storey, destroying it completely and Firoz Shah Tughlaq carried out restoration work replacing the damaged storey with two new storeys every year, made of red sandstone and white marble.
Split into simpler sentences: In 1369, lightning struck the top storey, destroying it completely. So, Firoz Shah Tughlaq carried out restoration work replacing the damaged storey with two new storeys every year, made of red sandstone and white marble.