Congratulations for saving such a sum at a young age. I'm 34 this year and i'm sad to say I do not have this amount in cash yet but it is coming this year.
I will suggest you get a book called, "Investing for Dummies" it is a very easy read and pretty much covers all aspects of investemnts in our lives. However, if you are too busy to do that, here's what I will suggest:
1. Putting your money in the bank earns you about 2% p.a. or less in a year (here in Singapore) and inflation rate is more than 3%. This means that the value of your money is shrinking. However, if you may need this money in the next 1 or 2 years, this may be the best idea as it is relatively risk free.
2. The investment that gives the highest Return on Investment (ROI or most "interest") is alwasy investing in yourself, or a business. You are still young and will be generating income for the next 20 to 30 years, it makes good sense for you to take a portion of that money to:
a. upgrade yourself professionally, which will ultimately increase your pay (if you work for people),
b. invest in a business, if you have a business idea; or partner with someone trustworthy (make sure he is trustworthy and get a lawyer to do up the agreement properly).
However, most businesses will not give you good cash flow in the 1st year or so (varies from business to business) and there is a huge risk taken when starting a business (about 1 in 5 business do not make it past the 1st year).
3. Investing in a property makes a lot of sense for long term. In singapore, a lot of very wealthy businessmen use properties as a form of investment to safeguard their wealth. It is used by only very wealthy people due to the fact that it involves large amounts of money.
Search for a good property, (one that you will stay in it yourself), talk to to your friends or relatives who own their own property (or a few properties) to seek their advice, get a reliable agent and find a suitable property at the right price.
Do it up decently and lease it out! You have to get it at a good price (i'm not sure if the property prices are good at this time where you are staying), the rent that you collect have to cover the installements that you pay and give you positive cash flow. At the same time, the value of your house will increase over time (most properties appreaciate over long periods of time).
However, investment in properties are usually a big sum and you will have to do more research and be patient to shop for a good buy. Also there is a risk that your house will be untenanted and you will have to fork out the monthly installments in cash. That's negative cash flow.
4. If you do not want to invest such a huge sum on properties, you can take up some unit trusts, not those that carry insurance, they charge you mortality charges even if their funds are losing money! Unit trusts without insurance element give much better renturn on investment (I am assuming that you have adequate insurance coverage, if you do not have please find a financial advisor and get insured).
Over a period of 5 to 10 years, it is safe to say that most unit trusts will generate about 10% a year (sometimes more over a shorter time, depending on market movement).
Hope this helps =)