- Old Jefferson Town House
- 7 Gardiner Rd, Jefferson, ME
- Old Walpole Meetinghouse
- Walpole Meeting House Road, Walpole, Maine
- Old Wiscasset Jail and Museum
- 133 Federal St, Wiscasset, Maine, 04578
- Opera House in Boothbay Harbor
- 86 Townsend Avenue, Boothbay Harbor
- Otyokwa Cabins
- 244 Nobleboro Road, Bremen
- Owls Head Transportation Museum
- 117 Museum St., Owls Head
- Owls Head Transportation Museum
- 117 Museum St., Owls Head
- Oxbow Brewing Company
- 274 Jones Woods Road, Newcastle, Maine, 04553
- Oysterhead Lounge - Newcastle Publick House
- 51 Main St., Newcastle
- Oysterhead Lounge at Newcastle Publick House
- 52 Main St, Newcastle, ME, 04553
