Building or Land:
Purchase or construction of a building
Consider the houses 4, 11, and 12 for purchase or construction of a building (4th is the main house for building, 11th gain, 12th payment to the seller of the building or investment of money).
Disposing of the building or selling it
Consider the houses 3, 5 and 10 for disposing of the building or selling it (3rd is 12th from the 4th i.e. losing the house; 5th is 11th from the 7th i.e. gain to purchaser; 10th is 4th from the 7th i.e. building to the purchaser)
Mars is the natural significator of buildings and Saturn is that of land, mines and estates.