For the thousands of Democratic conventioneers, SEPTA will spruce up the dilapidated subway and trolley stations and concourses beneath City Hall.

However, the long-delayed, $150 million overhaul of the City Hall Station and 15th Street Station won't happen until after the crowds leave town, SEPTA officials said Thursday.

The subways will get cosmetic improvements this summer, in time for Pope Francis' visit, and will be touched up again in 2016 before the Democrats arrive in July.

That work will include resurfacing the City Hall Station platform, painting the walls, and improving the lighting in the concourses and stations. Signs will be upgraded.

The Broad Street Line, which will move thousands of conventioneers between Center City and the Wells Fargo Center in South Philadelphia, will get "targeted heavy maintenance" on tunnels, platforms, and concourses between the Race-Vine Station and the southern end of the line at AT&T Station.

Similar work, including painting and graffiti-removal, will be done along the Market-Frankford Line from Second Street Station to 30th Street Station.

SEPTA last month announced plans to remake the subterranean complex beneath City Hall, starting next year and lasting until 2020.

The start of work in 15th Street Station, planned for March or April 2016, will likely be delayed to avoid interfering with the out-of-town visitors, SEPTA spokeswoman Jerri Williams said Thursday.

The massive overhaul of the century-old 15th Street Station on the Market-Frankford Line and the 87-year-old City Hall Station on the Broad Street line will make the stops roomier, brighter, and cleaner, and equip them with elevators to make them fully accessible.

The dilapidated subway complex is the city's busiest: About 29,000 riders enter the two stations through the turnstiles each weekday, and thousands more use the free interchange that links the subway lines and the trolley tracks beneath City Hall.