Impluvium is a part of Roman architecture. It is an architectural technique in which the floor is made comparatively lower than the other part of the floor to create a pool for collecting rain water.  It can be seen usually in Greek and Roman houses where a part of the floor is dipped and made open and hollow. This is designed in such a way that the rainwater that falls on the roof is carried through compluvium of the roof and gets deposited and settled to the pool made of marble. Usually this sunken part is built 30 cm below the floor of the porch.