The Patarei sea fortress and prison, which has been mostly abandoned since 2002, when the prison was shut down, has attracted interest from a number of foreign investors.
State Real Estate, which owns the 4-hectare seaside property, said it will wait for the approval of a detailed plan.
The state attempted to sell the property with a initial price of 3 million euros two years ago, but received no bids. Märt Mäe of State Real Estate, said the price now will be significantly higher than the 3 million euros.
Mäe told Pealinn potential suitors from Estonia, Finland, Sweden and even Singapore have popped up recently.
The complex, built in 1840, need restoring as buildings have began to crumble. First commissioned as a sea fortress, it was turned into army barracks in 1867 and after 1920 operated as a prison housing, among others, political prisoners from the failed 1924 communist uprising.