Fill some of the empty windows in derelict buildings with colorful artworks. These could each be made individually by artists, or they could all combine to make one cohesive artwork. Buildings would be chosen by the team based on impact to community and landlord interest.
This is a low-cost, temporary way to make derelict buildings more attractive prior to their redevelopment. It may draw attention to the building for investment, or it might brighten up the street the building is on leading to investment in neighboring buildings. It will also promote Lowell as an art-friendly city!