Ghats, verandahs, chabutaras, rooms, main lake, 9- sub lakes are different parts of Gadisar lake which makes it an amazing piece of architecture and add on to its beauty.
Primary motto behind constructing Gadisar lake was to fullfill water needs of local people, so according to me lake is the most usefull part of it.
Rooms surrounding lake were used as schools, so again it is a usefull part of it. Indeed, every part of Gadisar has its own significance in itself.