Channel lights are always built in pairs, and the entrance to the channel approach at Baltimore actually has two sets of channel lights known as the Craighill Range Lights. Located in Chesapeake Bay at the entrance to the Patapsco River, the Craighill Channel was named for an engineer and longtime member of the lighthouse board, and cuts some five miles off the southern approach to Baltimore.

The earlier of the two sets are the Craighill Lower Range Lights, established in 1873, followed some dozen years later by the Craighill Upper Range Lights. Ironically, the Lower Range lie North of the Upper Range pair!

The manner in which range lights are placed is at different heights, aligned to mark the entrance to a ship channel. The Front Range at Craighill was the first caisson light built in the United States, and is located about two miles from the rear light. The Rear Lower Range Light, which Harbour Lights depicts as it stood at its prime, was originally planned as a screwpile, but ice-related problems caused the lighthouse board to recommend a "more solid" structure.

This required building a cofferdam in two feet of water and laying nine granite, supporting piers. On these piers, a 105-foot, four-sided iron frame enclosed a two-story Victorian keepers house with a rectangular tower rising through the center. It was accented with two levels of balconies by the lantern and its architecture was unique in the Bay. The original design was described as a "pagoda-like curved roof with eight dormer windows built within the base."

An 1888 summer storm tore the roof from the distinctive dwelling, in addition to doing some other damage. In the 1930s, the structure was totally dismantled, leaving the white and red tower, lantern and square stairway shaft.

Its original optic, still in use, is a Fourth Order Fresnel Range Lens. The light was automated in the 1930s at the same time the dwelling was eliminated. Its beacon is a fixed white light that can be seen for 16 nautical miles.