 Greens Ledge Lighthouse is a sparkplug lighthouse in Connecticut , United States , off the southwest end of the Norwalk Islands , Long Island Sound , near Norwalk , Connecticut . It is on north side of the west end of Greens Ledge , west of Norwalk Harbor a mile south of the entrance to Five Mile River at Rowayton , and just over a mile southwest of Sheffield Lighthouse . Completed in 1902 , it was constructed by the Philadelphia Construction Company . The light is 52 feet ( 16 m ) tall and is made of five courses that make up its four stories . The lantern measures 7 feet ( 2 @.@ 1 m ) in diameter . The Greens Ledge Light replaced the Sheffield Island Light . Originally , the light had a fifth @-@ order Fresnel lens , but a fourth @-@ order Fresnel lens was installed in May 1902 , just three months into its operation . Currently a VRB @-@ 25 is in use and it has alternating white and red flash every 24 seconds . The light was added to the National Register of Historic Places as Greens Ledge Lighthouse on May 29 , 1990 . 
 Greens Ledge Lighthouse <a href='drop_aux' title='1'><mark>is</mark></a>a sparkplug lighthouse in Connecticut , United States , off the southwest end of the Norwalk Islands , Long Island Sound , near Norwalk , Connecticut . It is on north side of the west end of Greens Ledge , west of Norwalk Harbor a mile south of the entrance to Five Mile River at Rowayton , and just over a mile southwest of Sheffield Lighthouse . Completed in 1902 , it was constructed by the Philadelphia Construction Company . The light <a href='drop_aux' title='2'><mark>is</mark></a>52 feet ( 16 m ) tall and is made of five courses <a href='null_relcl' title='3'><mark>that</mark></a>make up its four stories . The lantern <a href='uninflect' title='4'><mark>measures</mark></a> 7 feet ( 2 @.@ 1 m ) in diameter . The Greens Ledge Light replaced the Sheffield Island Light . Originally , the light had a fifth @-@ order Fresnel lens , but a fourth @-@ order Fresnel lens was installed in May 1902 , just three months into its operation . Currently a VRB @-@ 25 <a href='drop_aux' title='5'><mark>is</mark></a>in use and it <a href='uninflect' title='6'><mark>has</mark></a> alternating white and red flash every 24 seconds . The light was added to the National Register of Historic Places as Greens Ledge Lighthouse on May 29 , 1990 . 
Greens Ledge Lighthouse a sparkplug lighthouse in Connecticut , United States , offf the southwest end of da Norwalk Islands , Long Island Sound , near Norwalk , Connecticut . It is on north side of tdawest end of Greens Ledge , west of Norwalk Harbor a mile south of the entrance to Five Mile River at Rowayton , and jus ova a mile southwest of Sheffield Lighthouse . Completed in 1902 , it was constructed by thdahiladelphia Construction Company . The light 52 feet ( 16 m ) tall and is made of five courses make up its 4 stories . The lantern measure 7 feet ( 2 @.@ 1 m ) in diameter . Thedaeens Ledge Light replaced the Sheffield Island Light . Originally , the daht had a fifth @-@ order Fresnel lens , but a fourth @-@ order Fresnel lens was installed in May 1902 , just three months into its operation . Currently a VRB @-@ 25 in use and it have alternating white and red flash every 24 seconds . The light was added to the National Register of Historic Places as Greens Ledge Lighthouse on May 29 , 1990 .