PORTLAND (AP) — Two lighthouses off the coast of Maine are being auctioned by the federal government.

The Portland Press Herald (http://bit.ly/1guOnwA ) reported that Halfway Rock Light Station off Harpswell and Boon Island Light Station off York went on sale Wednesday, as part of a federal program to rid the government of the expensive-to-maintain structures.

Private buyers must agree to several federal conditions.

Each one must continue to be a navigation aid for boat traffic, meaning the U.S. Coast Guard will come by from time to time to do maintenance.

Halfway Rock, built in 1871, features a 76-foot-tall tower, which once had keeper’s quarters, on two acres of ledge about 10 miles out. Boon Island was built in 1855 and features a 133-foot tower on a tiny island about six miles offshore.