Brno is a city in the South Moravian Region of the Czech Republic. Located at the confluence of the Svitava and Svratka rivers, Brno has about 403,000 inhabitants, making it the second-largest city in the Czech Republic after the capital, Prague, and one of the 100 largest cities in the European Union. The Brno metropolitan area has approximately 730,000 inhabitants.

Brno served as the capital of Moravia from the Middle Ages until 1948, and remains the political and cultural hub of the South Moravian Region. Brno is an important centre of the Czech judiciary. The Constitutional Court, the Supreme Court, the Supreme Administrative Court, the Supreme Public Prosecutor's Office, as well as state authorities, such as the Ombudsman and the Office for the Protection of Competition, are all located here. Brno is also an important centre of learning and higher education, with 10 universities, 29 faculties and a student population of over 65,000, as well as more than 60 secondary schools throughout the city.

The Brno Exhibition Centre is one of the largest in Europe. The complex opened in 1928 and has a long history of hosting international trade fairs and expositions. The Masaryk Circuit has been hosting motorsport events since 1930, including the Road Racing World Championship Grand Prix. Another local tradition is the international fireworks competition and drone show Ignis Brunensis, which attracts over a million visitors annually.

Brno's traditional symbols are two medieval landmarks which dominate the cityscape: the historic Špilberk Castle and its fortifications, and the Cathedral of Saints Peter and Paul on Petrov Hill. Another historic landmark is the Veverí Castle near the Brno Reservoir. The Villa Tugendhat, a seminal example of functionalist architecture, was added to the UNESCO World Heritage Sites List in 2001. One of the natural sights outside the city is the Moravian Karst. Brno is a member of the UNESCO Creative Cities Network and was designated a "City of Music" in 2017.

The etymology of the name Brno is disputed. It might be derived from Old Czech brnie, i.e. 'muddy', 'swampy'. Alternatives are the Slavic verb brniti ('to armour' or 'to fortify') or a Celtic origin. The latter theory would make it cognate with other Celtic words for hill, such as the Welsh word bryn. Throughout its history, locals in Brno have also referred to their city in different languages, including Brünn in German, Brin in Yiddish, and Bruna in Latin. The town was also referred to as Brunn in English, but this variant is no longer common today. The asteroid 2889 Brno was named after the city, as was the Bren light machine gun. The latter was in wide use during World War II, and its name derives from 'Brno' and 'Enfield', the site of the Royal Small Arms Factory.

Brno has over 400 protected cultural sites and objects, including one designated as a UNESCO World Heritage Site, and 14 monuments on the List of national cultural monuments of the Czech Republic [cs]. Most of them are in the historical city centre, but some are located in the outer districts of the city.

The Old Town Hall (Czech: Stará radnice), dating back to approximately 1240, is the oldest secular building in Brno and has been registered as a national cultural monument since 2024. Its observation deck is 63 metres above ground, and the central passageway houses the Brno dragon and a cartwheel, both symbols of the city. Špilberk Castle, originally a royal seat founded in the 13th century, became a fortress and later a prison from the 17th century onwards (e.g., the Carbonari). Today, it is one of the city's major landmarks. The park and gardens around the castle, established in 1861, are notable for their landscaping, as well as an observation point also known as the Špilberk Arbour.

Another key landmark is the Cathedral of St. Peter and Paul, located on Petrov Hill. The site initially housed an 11th-century Romanesque chapel, which was rebuilt into a Romanesque basilica in the 13th century. The exterior of the cathedral was rebuilt as a three-nave Gothic basilica in the 14th century. Further modifications followed in the 15th and 16th centuries. The interior is mostly Baroque, as a result of extensive renovations in the mid-18th century. The structure was completed in its present form, including the addition of two distinct Neo-Gothic towers designed by architect August Kirstein [de], in 1909. The cathedral is a national cultural monument and its image is featured on the Czech 10-koruna coin.

Veverí Castle, about 20 km (12 mi) from the city centre, is the third-largest historic monument in Brno. Founded in the Middle Ages as a hunting lodge for the Moravian margraves, it is among the largest and oldest castles in the Czech Republic. Its last owner was Baron Maurice de Forest, an early motor racing driver, aviator, and close friend of Winston Churchill, who visited the castle several times.

The Abbey of Saint Thomas, the site of Gregor Mendel's genetics experiments, is also linked with Leoš Janácek. The Church of Saint Tomas houses the graves of John Henry, its founder, and his son, Jobst of Moravia, both margraves of Moravia. The Basilica of the Assumption of Our Lady is the final resting place of Queen Elisabeth Richeza. The Church of Saint James is one of the best-preserved Gothic churches in Brno.

The Brno Ossuary is the second largest in Europe after the Catacombs of Paris. Another smaller ossuary is the Capuchin Crypt, which houses mummies of Capuchin monks and other notable figures of their era, including architect Moric Grimm [cs] and the mercenary leader Baron Trenk. The Labyrinth under Zelný trh, a system of underground corridors and cellars dating back to the Middle Ages, have historically served as beer and wine cellars, food storage, and wartime shelters, and have more recently become a tourist attraction. They were previously not as interconnected as they are now, following an extensive reconstruction completed in 2009.

Brno was home to a sizable Jewish community since at least the 13th century. The city is home to a functionalist synagogue built between 1934 and 1936, and the largest Jewish cemetery in Moravia. Tombstones and other cemetery artifacts date back to 1349. It is estimated that the Jewish community comprised about 12,000 individuals in 1938. Only about 1,000 of them survived the Holocaust and Nazi persecution during World War II. The cemetery and the synagogue are maintained by Brno's remaining Jewish community. The only mosque in the Czech Republic, founded in 1998, is also located in Brno.

The interwar period saw a significant construction boom, as evidenced by numerous modernist and functionalist buildings. The Villa Tugendhat, designed by architect Ludwig Mies van der Rohe in the 1920s for the family of Fritz Tugendhat [cs], was completed in 1930. It was designated a UNESCO World Heritage Site in 2001. Another notable architect who significantly contributed to Brno's cityscape was Arnošt Wiesner. Other examples of functionalist buildings include the Hotel Avion [cs] and Palace Moravia. The Brno Exhibition Centre hosts more than 40 trade fairs and conferences annually, attracting over 1 million visitors.

Luzánky is the oldest public park in the Czech Republic, established in the late 18th century by Emperor Joseph II. Denisovy sady [cs], founded in the early 19th century, was the first public park in the Czech Republic to be established by public authorities. More recent additions include the Brno astronomical clock and the AZ Tower, commissioned in 2013, and at 111 metres (364 ft), the tallest building in the Czech Republic.