CAPE ELIZABETH — Some visitors will get a peek at the inside of the tower of Portland Head Light next month.

The tower will be open to visitors on Open Lighthouse Day, which takes place Sept. 18. Capacity is limited and tickets will be distributed on a first come first served basis.

Twelve tickets will be available for each 15-minute period between 9 a.m. and 3 p.m. Each ticket is good only for the time period printed on the ticket. Visitors must be able to climb more than 85 steps without assistance. Children under 10 will not be admitted to the tower.

The museum in the former keeper’s quarters will be open and free that day.

Open Lighhouse Day is an effort of the state Office of Tourism, the Coast Guard and the American Lighthouse Foundation. Twenty-five lighthouses are participating this year.

For more information, go to www.lighthouseday.com.