This bus line was launched for the occasion of 20th Museums' Night that took place on 18 May 2024 and it operated only on that day. Through this night, there were several special bus and tram lines in Warsaw (all lettered), of which A, P, R and M were served by old vehicles not in service from several years if not even decades, while the rest - B, C, D, E and F were served by modern-day vehicles (i.e. those you can see on Warsaw's streets every day). All lines were free of charge.

Schedules of all special lines from Warsaw Public Transport Authority website (in Polish) are here.