The sale of tenancy rights will attract Long Term Capital Gains Tax with zero cost of acquisition.
However, if you have claimed depreciation on the structure, the difference between sale consideration and wdv of block of asset shall be trated and taxed as Short term capital asset. So please be mindful while assigning value to the structure as more the value, more you have to pat STCG tax which is higher than long term capital gains tax.
further you can claim exemptions agains the long term capital gain which are not available in the case of STCG.