The Two Harbors Lighthouse is the oldest operating lighthouse in Minnesota. The station was completed in 1892 and overlooks Agate Bay, one of the two harbors that Two Harbors is named after. The station is now a combination of museum and bed & breakfast that is operated by the Lakes County Historical Society.

The lighthouse as it appeared in the fall of 2012.

The current light apparatus in the lantern of the Two Harbors Lighthouse, Fall 2012.

That apparatus is a pair of DCB-244 aerobeacons that were installed in 1969. The original lens (or perhaps lenses) was a fourth order fresnel lens. From here, the history is a bit murky. Some sources list the original lens as being a rotating four panel lens that was installed in 1892 and remained in service until 1969. Other sources show that the original fourth order lens was a fixed lens and that it was replaced in 1907 with the above described four panel lens. What I can say for sure is that a four panel fourth order lens was removed from the lantern in 1969 and is now on display at a museum in Ohio.

The fog signal building, Fall 2012. The fog signal building is used as a gift shop today. When the station was in operation, this building housed the equipment for a fog signal. The original fog signal was a pair of steam whistles. In the 1920s, the whistles were replaced with a diaphone. All of the fog signal equipment is now gone, except for the trumpets mounted on top of the building. The signals were discontinued in the early 1970s.

References:
http://www.uscg.mil/history/weblighthouses/LHMN.asp
http://www.lighthousefriends.com/light.asp?ID=267