The Ringstrasse or Ringstraße (pronounced [ʁɪŋˌʃtʁaːsə] ^ⓘ, lit. ring road) is a 5.3 km (3.3 mi) circular grand boulevard that serves as a ring road around the historic city centre, the Innere Stadt, of Vienna, Austria. The road is built where the city walls once stood. The Ring, as it is colloquially known, was built, along with grand buildings on either side of the road, in the second half of the 19th century. The road runs clockwise, from the Urania to the Schottenring, and is divided into nine parts.

Because of its architectural beauty and history, the Ringstrasse is designated by UNESCO as part of the Historic Centre of Vienna World Heritage Site.

The grand boulevard was constructed to replace the city walls, which had originally been erected during the 13th century. These walls were initially funded by the ransom payment obtained from the release of Richard the Lionheart, King of England, who had been captured near Vienna on his return from the Third Crusade. The fortifications were subsequently reinforced following the Ottoman Siege of Vienna in 1529 and the Thirty Years' War in 1618. The walls were surrounded by a glacis approximately 500 meters wide, where construction and vegetation were prohibited for military defensive purposes.

By the late 18th century, these fortifications had become obsolete. Under the reign of Emperor Joseph II, streets and walkways were developed within the glacis, illuminated by lanterns and lined with trees. Craftsmen established open-air workshops, and market stalls were set up in the area. However, it was the Revolution of 1848 that brought more significant changes, leading to the eventual transformation of the space into the grand boulevard it is today.

In 1850, the suburbs, known as Vorstädte (now comprising Districts 2 to 9), were incorporated into the municipality. This expansion made the city walls an obstacle to traffic. Consequently, in 1857, Emperor Franz Joseph I issued the decree "Es ist Mein Wille", ordering the demolition of the city walls and moats. The decree not only ordered the removal of these fortifications but also detailed the dimensions of the new boulevard and specified the locations and functions of the planned buildings.

Aristocrats and other wealthy private individuals rushed to have prestigious Ringstraßenpalais (Ring Road palaces) built in the historicist style, known as Ringstraßenstil (Ring Road style). One of the first buildings was the Heinrichhof, designed by Theophil von Hansen, which stood until 1954, having been damaged in the Second World War .

The construction work on the Ring was not finished until 1913 with the completion of the Ministry of War, when the Ringstraßenstil had already become unfashionable, as shown by the Postal Savings Bank building opposite, built by Otto Wagner in Art Nouveau in 1906.

The Ringstrasse and its accompanying structures were envisioned as a testament to the grandeur and glory of the Habsburg Empire. On a practical level, the construction of the Ringstrasse was influenced by Emperor Napoléon III's urban planning in Paris, where the widening of streets had proved effective in preventing the erection of revolutionary barricades, thus facilitating artillery control.