Published: Sep 06, 2010 7:35 PM EDT
Updated: Sep 06, 2010 4:29 PM EDT

NEW YORK (AP) - Colleges around the country are buying up large chunks of land without always having a clear idea of how it will be used.

The colleges are banking on growth in the years or decades to come. They are leasing the properties out or just letting them sit until they need them.

Columbia University President Lee Bollinger says he doesn't know what all the space will be used for, yet. He says he is letting future generations decide what to do with the space.

Columbia has amassed more than 17 acres in Manhattan's Upper West Side. Bollinger says all the space won't be used for academic purposes for at least 30 years.

Experts warn that investing in real estate can be risky.

Several colleges say the benefits outweigh the risks.