We start our Spain trip by spending 3 days in Madrid. After spending time subsequently in Granada, Malaga, Ronda, Seville and Lisbon, we fly back to Madrid on a Saturday night (Arrival 22:40 hrs at Terminal 4), and we have an international connection to catch at 6:30 am next morning from Terminal 1. We have decided that there is no point looking for a hotel for 4-5 hours. We want to leave our luggage at the airport and hop over to town to party away for 3-4 hours. Our questions are:
1. Should we leave our luggage at the Left Luggage counter of T4 or T1 ? People with experience of handling the Barajas airport may kindly reply.
2. I guess we will get the metro at around midnight to get into Madrid downtown. Till what time does the metro run (to enable us to get back to the airport by 4 am) ? If the metro is not running at that hour, is it easy to find a cab from downtown to the airport at that hour on a Saturday night?
Thanks for your help in advance.


there are 2 metro stations serving Barajas airport:
-one for terminals 1, 2 and 3 (same station for the 3 terminals)
-another one for terminal 4
Both stations are located within the same metro line (line 8)
Metro runs form 6,00 am til 1,30 am, therefore you won't be able to get to the airport by metro at 4,00 am. It will be relatively easy to find a cab on saturday night, but bear in mind lots of people will be trying to get a cab at that time so allow some time to find a free taxi (and look for it at taxi stops or main streets)
I don't know how the lugagge storage works, but since your flight leaves from terminal 1 I suppose it would be much more convenient to leave your lugagge there before going to party and pick it up next morning.

Check with the company you're flying if you can check in the previous night, you will save the left luggage fee and can arrive later to the airport in the morning.
About cabs in madrid a saturday night around 3-4, it's quite difficult to get one, if you're downtown you have to walk to Plaza Cibeles or to Plaza España to have a chance, the area between these squares is packed with night bars, clubs,discos and there're a lot of people searching a taxi.