The UEFA Champions League is the most prestigious title in club football, and has been running since 1955, although it has had many changes to the tournament over time.
The 2015/16 final was held at the San Siro in Milan, Italy.
Real Madrid eventually beat Atletico Madrid 5-3 on penalties after extra time being played following a 1-1 score.
Did you know Real Madrid's all-time leading scorer Raúl González started his career at Atlético? Ahead of their semi-final, UEFA.com looks who else has represented both clubs.
With Atlético and Real Madrid set for their seventh and eighth UEFA club competition encounters in the semis, UEFA.com remembers the fixtures that took age-old rivalries to the biggest stages.
Juventus keeper Gianluigi Buffon is again within sight of a first UEFA Champions League title of his career – but is he currently the best player never to have won it? VOTE NOW!
Real Madrid made a sluggish start but, with Cristiano Ronaldo firing on all cylinders, the dream of becoming the first team to retain the UEFA Champions League title is fully alive.
Real Madrid kept pace with Barcelona at the top of the Liga with an emphatic away win, while Monaco went down to a heavy defeat in the French Cup semi-finals.
It's been business as usual for Diego Simeone's side as they go quietly and impressively about their work. Runners-up in two of the past three seasons, will it now be third time lucky for Atleti?
At 18 years and 120 days old, Monaco's Kylian Mbappé has already scored five UEFA Champions League goals and set a competition record; UEFA.com charts his stunning progress so far.
Monaco have lost both previous ties against Juventus, who have never been beaten in a two-legged contest against a French club as they bid for a second final in three seasons.
Real Madrid ended Atlético Madrid's UEFA Champions League hopes in each of the last three seasons, including the 2014 and 2016 finals, and are out to make it four in a row.
All yellow cards accrued by players in the UEFA Champions League and UEFA Europa League since the start of the group stage have been wiped out ahead of the semi-finals.
Won most by: Real Madrid (10 times)
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