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Built in 1807, the Portland Observatory is the last surviving maritime signal tower in the United States. Featuring an octagon shape, the observatory stands over 86 feet tall and it is 222 feet above sea level. Throughout its long history, the observatory would use both telescopes and signal flags to communicate to ships regarding the upcoming docks. Because of its shape as well as its two-way communication system, the Portland Observatory carries a maritime history now lost throughout the United States. In fact, this Observatory is the only known remaining maritime signal tower in the country. Nowadays, the Greater Portland Landmarks operates the historic Observatory as well as its accompanying museum. Visitors can often find educational programs and seasonal guided tours, while in the museum, the many interpretive exhibits highlight the tower’s history and the preservation processes. From Memorial Day to Columbus Day, Greater Portland Landmarks uses knowledgable docents to give guided tours throughout the building, providing history and maritime buffs with a comprehensive and exciting story. The Portland Observatory was added to the National Register of Historic Places in 1972, and in 2006, it was made a National Historical Landmark.


  • Outside View of the Portland Observatory
  • Portland Observatory in 1936
  • Inside the Portland Observatory
  • View From the Top of the Observatory

History of the Portland Observatory

The history of the Portland Observatory, as well as the early history of Maine following the Revolutionary War, can be traced back to Captain Lemuel Moody. Although he was only eight when the war broke out in 1775, Moody began working two years later as a water boy with Captain Joseph Pride and Captain John Reed. 

This early experience at sea shaped the rest of Moody’s life, and after the war, Moody left the shore to make a career as a sea captain. At the time (and although Portland was a Province of Massachusetts until 1820), Portland was one of the fastest growing port cities in the young United States. 

Moody witnessed the growth of both the Portland marina as well as those of other cities, and he knew that to keep pace, Portland needed a tower so that he could view approaching vessels and alert the waterfront. 

After forming the Portland Monument Ground to finance the tower and choosing the top of Munjoy Hill as its location, Moody was able to build the Portland Observatory by 1807. Known as the “Brown Tower,” the Observatory was a familiar sight in the city. 

Architectural Features and Function

Although the eight-sided octagonal design for the tower may seem stylish to modern eyes, the very shape of the Observatory was essential for withstanding the harsh winds and weather blowing off the Atlantic. 

The base of the structure measures 32 feet across, and it stands 86 feet tall. Within the base of the observatory, 122 tons of granite and heavy crossbeams secure and stabilize the tower. The skeleton of the Observatory includes eight 64-foot white pine timbers. 

To monitor and identify ships so that he could alert the wharf of their arrival, Moody used a large telescope. When he needed to relay certain messages to the dock, he would fly sets of specifically defined from two flagpoles. Later, a third flagpole was added. By reading the groupings of flags, dockworkers would know which type of ship was approaching and how much dock space they need to reserve. 

Because Moody was a captain and spent significant time atop the observatory, he also used the structure as a weather station and took careful temperature readings three times a day. From the beginning, the tower was also a tourist attraction and city landmark, and Moody would sometimes allow tourists to walk the 102 (now 103) steps to the top of the tower for a small fee.1 

1.) http://www.mainememory.net/pdf_files/LemuelMoody.pdf