Picking an all-time XI for either one of the Madrid sides is hard enough, but picking a combined XI? Near enough impossible.
The list of players who learnt their trade, cemented their status in the football hall of fame, or even finished off their trophy-littered careers in the Spanish capital is endless. So we've done the hard bit for you and narrowed down the shortlist.
GK - Iker Casillas (Real Madrid)
Only one choice for this spot really. Casillas is one of the greatest goalkeepers of all time and his trophy cabinet is absolutely heaving. Debut at 17, Champions League winner by 19 and over 500 appearances over 16 years.
Extraordinary cat-like reflexes and a man-mountain in between the sticks (despite only being 6ft). All hail 'San Iker."
RB - Michel Salgado (Real Madrid)
Former Real Madrid teammate Steve McManaman once described Salgado as "the hardest person in the world...a genuine psychopath, even in training."
If you add that to his decade-long stint at Real, re-defining how a right-back should play and holding aloft four La Liga trophies and two Champions Leagues - he owns the right-back spot.
CB - Diego Godin (Atlético Madrid)
Much of Atlético's resurgence can be filtered back to the steady foundations of Diego Godin. Since his move from Villarreal in 2010, Godin matured into one of the world's best centre-backs.
Simeone's defensive management style is synonymous with Godin's aggressive style of play. Solid in the air, not scared to get stuck in and always has the surprise element of bursting through with the ball.
CB - Sergio Ramos (Real Madrid)
He really is like Marmite, Sergio. The master of the dark-arts, win-at-all-costs, ultimate sh*thouse. But he's Real's beloved sh*thouse.
He's been a force of nature during his time at Madrid and has helped them to a lot of trophies, and when the dust settles, he's pound-for-pound one of the best centre-backs in world football.
LB - Roberto Carlos (Real Madrid)
It's pretty sad that there is a generation of football fans who won't have seen Roberto Carlos don the all-white strip. That left peg must be worth a fortune.
Former Real Madrid coach Vicente del Bosque said "Roberto Carlos can cover the entire [left] wing all on his own," perhaps one of the most attacking-minded full-backs of a generation and boy, he could hit a set piece.
RW - Cristiano Ronaldo (Real Madrid)
Does this one need justifying? One of the best footballers of all-time.
Rather than giving the opinion of 'just some guy', here's what George Best had to say about him: "There have been a few players described as the new George Best over the years, but this is the first time it's been a compliment to me."
CM - Adelardo Rodriguez (Atlético Madrid)
Adelardo is plausibly Atlético's best ever midfielder, holding the club record for appearances to this day with 551. He enjoyed a 17-year spell in the Spanish capital from 1959 to 1976.
Probably one of the best complete midfielders of his time, combining skill, commitment and a knack for goalscoring.
CM - Zinedine Zidane (Real Madrid)
It's 2002, Zidane's only just balding and he's sporting those gorgeous predators. Oh, when life was simple.
Zidane was a pure joy to watch, his ability to create space when there very clearly was incredible. Them predators were like two silk slippers, carefully moulded to his feet so he could pluck a ball straight from the clouds.
LW - Paulo Futre (Atlético Madrid)
Paulo Futre became a bonafide legend at Atlético where he spent six seasons. His explosive nature, dribbles and little twists and turns was adored by the crowd.
He attained comparisons to Maradona and it was easy to see why. An important generational Portuguese talent late 80s/early 90s.
ST - Ferenc Puskás (Real Madrid)
Ferenc Puskás' career was obviously before most people's time but the fact his legacy still stands is testament to a wonderful player.
Joining Real Madrid in 1957 at the grand old age of 31, Puskás scored four-hat tricks in just his first season. He won La Liga five years in a row from 1961 to 1966, scoring a total of 82 goals over that period. Not surprising the most beautiful goal award is now named after him, ey?
ST - Fernando Torres (Atlético Madrid)
Sometimes in life, things are just meant to be. You know, they just click. Fernando Torres was made for Atlético Madrid and Atlético Madrid was made for Fernando Torres.
Atlético's prodigy, native son and folk hero played a total of 404 times for Los Rojiblancos. A true example of the idea that trophies aren't everything, El Niño only won the Segunda División and the Europa League in Madrid.