Well, it grew up really well but that was "geologically easy". Madrid lies over a granitic floor, tunneling there is easier and faster than it would be in Barcelona, Amsterdam or London.

So, after having lived in Barcelona and Madrid... Both metros are excellent, but besides covering a smaller area, I still prefer Barcelona metro than Madrid one. IMHO, Barcelona metro looks more like the one in the german cities and Madrid metro looks like London one.

Said that, this year Madrid metro users have been quite angry at some line closures at the same time than tunnels were fixed at the same time in the city. It is mostly a managing problem as well, as some of the trains (quite old in some cases) are still being rented instead of bought.

Line 7B grew up as well but in San Fernando de Henares some buildings got structural cracks and some houses (over 50) had to be bulldozed.

Metro works from 06:00 to 01:00, but there is nothing before of after that time. In Barcelona, for instance, Monday to Thursday works 5:00 to 00:00, on Friday 5:00 to 02:00, and from 05:00 on Saturday to 00:00 on Sunday non-stop. That has been for some years now and means lots of drunk people not taking the car.

In Barcelona, metro schedules are tighter as well. In Barcelona, in rush hours you may have a train every 2,5 minutes, in some cases less than 2 minutes. In Madrid it's more like 4 minutes. Trains are newer in Barcelona, too (and wider because most lines use iberic gauge), but that was because until the 90s Barcelona trains had some asbestos on them.

Anyways, a metro is not only about the trains, it's also about the stations. Most of Madrid ones have conditioned air and have better lighting than not only the Barcelona ones, but the European ones as well. But, again IMHO, signage in Madrid metro is HORRIBLE. Most of the signs are on the walls, when you are walking on a crowded corridor is easy to take the wrong direction. I need a magnifier to read the metro plan on the wagons. Also, it takes some time to understand that it "drives on its left" in a country where everything else "drives on its right". Not a big thing, but if you come from somewhere in Europe it may take you some time until you get used to all of it.