About capital gain

Please elaborate .... your question is not clear.

Suppose I have a building and a land, when i sell the land i will go through capital gain, So i want to know that cant i invest the selling amount to my previous building for re-construction or development.

No... Exemption allowed in present case..... Exemption cab be allowed only if such amount from sale of land is invested in new house property and not existing one and that too on the condition that you own not more than one house property at time of sale of property and such land must have been your long term asset................... But there is one way that there will be no capital gain on sale of rural land..... Or is a urban land used for agricultural purpose for more than two years..... For more classification you can also read section 54b and 54f......