Buying a plot is a safer alternative. The price will go up as the demand increases, and we cannot manufacture land to meet the demand. Doubling the value  will depend on the location of the  plot . ' Investing ' in building/ apartment is not a good idea , according to me.  I am a firm believer that equity will outperform realestate in the long run.

Buying an open land,leaving it unattended for a long period may lead to encroachment problem.

For me there are 2 ways of channelising wealth.

1.Equities

2.Fixed Deposits/Bonds

I find other routes not quite impressive. Somehow, hate insurance to the hilt.Wont go for a mutual fund, as I am yet to come across a MF manager who has inspired me to beleieve that he is smarter than me in managing my money. Commodities in futures are hopeless, will like to play it physical whenever the urge becomes too high, otherwise indirectly by way of equities is fine with me. Real estate requires some muscular backing as basant sir has already said....when you have an easier way to make money why complicate matters....????????

Just as too much loyalty is a matter of dogs, similarly too much labour is a matter of porters.....