More development could be on the way along Washington Avenue on the west side of downtown St. Louis.

Already, Lucky’s Market is eyeing part of the ground floor of the Ely Walker building, at 1520 Washington, as a 20,000-square-foot grocery.

A much bigger development, however, appears to be in the works just west of the Ely Walker building, at the former CPI Corp. headquarters at 1706 Washington. Developer Michael Knight of Kansas City bought the vacant but historic building in January and plans to redo the nine-story building as apartments, officials say.

Knight had yet to respond to requests to discuss his St. Louis project. But sources say that his plan includes construction of a new building on the parking lot just east of the CPI building. Knight’s Monogram Building LLC owns both properties.

The plan includes 168 apartments in the CPI building — erected as the Monogram Building in 1912 — as part of a project that could eventually have about 500 market-rate and affordable apartments, sources said. The sources requested anonymity because the plan isn’t yet public.