The story of AC Sparta Prague began on 16 November 1893, when a group of young enthusiasts led by three brothers, Václav, Bohumil and Rudolf Rudl, founded a sports club in the Prague district of Královské Vinohrady under the name Athletic Club Královské Vinohrady. The blue, red and yellow tricolour flag was adopted almost immediately – in club tradition, blue stands for Europe, while red and yellow are the colours of the royal city of Prague. The famous red shirt, however, arrived later, thanks to Otakar Petřík, a committee member who in 1906 returned from London with a set of Arsenal kits, wishing the club to make them just as famous. Red shirts, white shorts and black socks have accompanied Sparta ever since, and its players are known as Rudí (the Reds).
A record 38 league titles (Czechoslovakia and the Czech Republic combined), together with 16 domestic cup triumphs, make Sparta the most successful club in the history of Czech football. The golden age came in the 1920s and 1930s, when the club's dominance earned it the nickname Železná Sparta (Iron Sparta). In 1927 Sparta won the first edition of the Central European Cup (Mitropa Cup), then the closest thing to today's Champions League, and repeated the feat in 1935 and 1964. Among the legends of the golden era were Karel Pešek-Káďa and Oldřich Nejedlý, while the 1960s, which brought the third Mitropa Cup, belonged to Andrej Kvašňák, later voted by supporters the Sparťan století (Spartan of the Century).
In European competition, Sparta wrote two memorable chapters. In 1972/73 the club reached the semi-finals of the Cup Winners' Cup, eliminating Standard Liège, Ferencváros and Schalke 04 before losing to AC Milan – all while enduring one of the worst domestic periods in its history, culminating in relegation in 1975, the only time it has dropped out of the top flight. An even bigger moment came in 1991/92, the last season under the European Cup name and the first with a group stage, often described as the zero edition of the Champions League. After eliminating Rangers (1-0 at home and 1-2 in Glasgow), Sparta met Olympique de Marseille, the previous season's runners-up, in the second round: beaten 3-2 away, the Prague side won the return leg 2-1 at Letná to advance on away goals.
In the group alongside eventual winners Barcelona, Benfica and Dynamo Kyiv, the defining moment came on 1 April 1992. In a sold-out Letná, Sparta, coached by Dušan Uhrin Sr. and playing in white shirts for the occasion, beat Barcelona 1-0 thanks to a 66th-minute goal by Horst Siegl. Supporters voted the match the Zápas století, the match of the century, in 2017. Only the group winner went through to the final, however; Sparta finished second with six points and a goal difference of 7-7.
Sparta have played at Letná since 1917, and although the stadium's commercial name has changed several times, for supporters it will always simply be Letná. All four stands now carry the names of club legends: the main stand honours Andrej Kvašňák, with the others named after Karel Pešek, Václav Ježek and Vlasta Burian. Sparta remains a regular in European competition, and its rivalry with Slavia, which dates back to 1896, is still one of the fiercest fixtures in Czech football.