Affectionately known as Bug Light, for its diminutive 24-foot tower, the Portland Breakwater Lighthouse in South Portland is the only one of its kind in the world.

Designed by Philadelphia-based architect Thomas Ustick Walter, who also designed the U.S. Capitol dome, Bug Light is a replica of the Choragic Monument of Lysicrates, which is located near the Acropolis in Athens, Greece.

Bug Light was built in 1875, although Congress first recognized the need for a lighthouse at the end of the nearly 2,000-foot Portland Breakwater as early as 1855, when a wooden light was erected.

The breakwater was built in stages in the 1830s to protect Portland Harbor after a fierce storm in 1831 destroyed much of Portland’s waterfront, including many wharves, ships and warehouses.

Bug Light may not be as well known as its neighbor, Portland Head Light in Cape Elizabeth, but it’s been marking the entrance to Portland Harbor for the past 140 years and its solar-powered light can still be seen by mariners miles out to sea.

Now owned by the city of South Portland and maintained by the South Portland-Cape Elizabeth Rotary, Bug Light is the crown jewel of the city’s park of the same name, which is located on the grounds of a former shipyard where Liberty ships were built in World War II.

During Saturday’s Maine Open Lighthouse Day, Bug Light drew a steady crowd of visitors all eager to see the view from the top of the structure, which included the opportunity to see the nearby Spring Point Ledge Lighthouse, as well as Fort Gorges and several islands in Casco Bay.

Since Bug Light is only open a handful of times each year, this weekend was a rare opportunity to see the lighthouse and learn something about its history, which is what drew the Edgar family from Gorham.

“We came here specifically to see the lighthouse,” said Amanda Edgar, who was there with her three young daughters.

Opening the lighthouse is not just fun for the public, but for the Rotary club volunteers, as well, who are led by Jack Roberts.

“I just really enjoying doing this,” Roberts said Saturday. “Especially seeing the kid’s faces just light up.”

He added, “This is a unique lighthouse, there’s no other one like this in the world. I just really enjoy opening it up, especially on such a beautiful day.”

Nancy Hawes, another member of the South Portland-Cape Elizabeth Rotary, said she likes volunteering for events like Maine Open Lighthouse Day because Bug Light offers “such a beautiful view and people really enjoy it.”

For volunteer Jim Britt the attraction of volunteering is being able to “meet people from all over the place.” In fact on Saturday there was at least one visitor from a foreign country – Germany.

In addition to a whale oil lamp, Bug Light also used to have a 1,000-pound bell that would ring during foggy weather. A two-room light keeper’s house was added in 1889, which was expanded to four rooms in 1903.

The first light keeper at Bug Light was W.A. Dyer, who served from 1855 to 1857, according to an informational plaque at the lighthouse. And the last keeper was Preston Marr, who ran the light from 1920 to 1934.

In researching the history of the lighthouse, Roberts learned that in 1934 an electric cable was run from the Spring Point Ledge Lighthouse to Bug Light and the light keeper at Spring Point was responsible for keeping both lighthouses operational.

Roberts said that the lighthouse went dark in 1942, following the attack on Pearl Harbor on Dec. 7, 1941, and remained dark until the Rotary Club was able to get the Coast Guard to relight it in 2002 – 60 years later.

The South Portland-Cape Elizabeth Rotary accepts donations to help maintain Bug Light. See www.sp-ce-rotary.org for more information.

The current Bug Light was built in 1875. The first lighthouse at the end of the Portland Breakwater was erected in 1855.Staff photos by Kate Irish CollinsAn informational sign tells visitors the history of Bug Light in South Portland.