Ljubljana is the capital and largest city of Slovenia. It has been the cultural, educational, economic, political and administrative centre.

During antiquity, a Roman city called Emona stood in the area. Ljubljana itself was first mentioned in the first half of the 12th century. Situated at the middle of a trade route between the northern Adriatic Sea and the Danube region, it was the historical capital of Carniola, one of the Slovene-inhabited parts of the Habsburg Monarchy. It was under Habsburg rule from the Middle Ages until the dissolution of the Austro-Hungarian Empire in 1918. After World War II, Ljubljana became the capital of the Socialist Republic of Slovenia, part of the Socialist Federal Republic of Yugoslavia. It retained this status until Slovenia became independent in 1991 and Ljubljana became the capital of the newly formed state.

The city's architecture is a mix of different architectural styles. Despite the appearance of large buildings, especially at the city's edge, Ljubljana's historic centre remains intact. Although the oldest architecture has been preserved from the Roman period, Ljubljana's downtown got its outline in the Middle Ages. After the 1511 earthquake, it was rebuilt in the Baroque style following Italian, particularly Venetian, models.

After the earthquake in 1895, it was once again rebuilt, this time in the Vienna Secession style, which today is juxtaposed against the earlier Baroque style buildings that remain. Large sectors built in the inter-war period often include a personal touch by the architects Jože Plecnik and Ivan Vurnik. In the second half of the 20th century, parts of Ljubljana were redesigned by Edvard Ravnikar.

The central square in Ljubljana is Prešeren Square where the Franciscan Church of the Annunciation is located. Built between 1646 and 1660 (the belltowers following later), it replaced an older Gothic church on the same site. The layout takes the form of an early-Baroque basilica with one nave and two rows of lateral chapels. The Baroque main altar was executed by the sculptor Francesco Robba. Much of the original frescos were ruined by the cracks in the ceiling caused by the Ljubljana earthquake in 1895. The new frescos were painted by the Slovene impressionist painter Matej Sternen.

Ljubljana Castle is a medieval castle with Romanesque, Gothic, and Renaissance architectural elements, located on the summit of Castle Hill, which dominates the city centre. The area surrounding today's castle has been continuously inhabited since 1200 BC. The castle was built in the 12th century and was a residence of the Margraves, later the Dukes of Carniola. The castle's Viewing Tower dates to 1848; this was manned by a guard whose duty it was to fire cannons warning the city in case of fire or announcing important visitors or events, a function the castle still holds today. Cultural events and weddings also take place there. Since 2006, a funicular has linked the city centre to the castle atop the hill.

Town Hall, located at Town Square, is the seat of the City Municipality of Ljubljana. The original building was built in a Gothic style in 1484. Between 1717 and 1719, the building underwent a Baroque renovation with a Venetian inspiration by the architect Gregor Macek Sr. Near Town Hall, at Town Square, stands a replica of the Baroque Robba Fountain. The original has been moved into the National Gallery in 2006. The Robba Fountain is decorated with an obelisk at the foot of which there are three figures in white marble symbolising the three chief rivers of Carniola. It is work of Francesco Robba, who designed numerous other Baroque statues in the city.

Ljubljana Cathedral, or St. Nicholas's Cathedral, serves the Archdiocese of Ljubljana. Easily identifiable due to its green dome and twin towers, it is located at Cyril and Methodius Square (Ciril-Metodov trg, named for Saints Cyril and Methodius) by the nearby Ljubljana Central Market and Town Hall. The Diocese of Ljubljana was set up in 1461. Between 1701 and 1706, the Jesuit architect Andrea Pozzo designed the Baroque church with two side chapels shaped in the form of a Latin cross. The dome was built in the centre in 1841. The interior is decorated with Baroque frescos painted by Giulio Quaglio between 1703-1706 and 1721-1723.

Neboticnik ("Skyscraper") is a thirteen-story building that rises to a height of 70.35 m (231 ft). It combines elements of the Neoclassical and the Art-Deco architecture. Predominantly a place of business, Neboticnik is home to a variety of shops on the ground floor and first story, and various offices are located on floors two to five. The sixth to ninth floors are private residences. Located on the top three floors are a café, bar and observation deck. It was designed by the Slovenian architect Vladimir Šubic. Construction began in July 1930 and the building opened on 21 February 1933. It was for some time the tallest residential building in Europe.