Trajan's Market (Latin: Mercatus Traiani, Italian: Mercati di Traiano) is a large complex of ruins in the city of Rome, Italy, located on the Via dei Fori Imperiali, at the opposite end to the Colosseum. The surviving buildings and structures, built as an integral part of Trajan's Forum and nestled against the excavated flank of the Quirinal Hill, present a living model of life in the Roman capital and a glimpse at the continuing restoration in the city, which reveals new treasures and insights about Ancient Roman architecture.

Thought to be the world's oldest shopping mall, the arcades in Trajan's Market are now believed by many to be administrative offices for Emperor Trajan. The shops and apartments were built in a multi-level structure, and it is still possible to visit several of the levels. Highlights include delicate marble floors and the remains of a library.

Trajan's Market was probably built in 100-110 AD by Apollodorus of Damascus, an architect who always followed Trajan in his adventures and to whom Trajan entrusted the planning of his Forum, and inaugurated in 113 AD. During the Middle Ages the complex was transformed by adding floor levels, still visible today, and defensive elements such as the Torre delle Milizie, the "militia tower" built in 1200. A convent, which was later built in this area, was demolished at the beginning of the twentieth century to restore Trajan's Markets to the city of Rome.

Trajan ( /ˈtreɪdʒən/; Latin: Marcus Ulpius Nerva Traianus Augustus; 18 September 53 – 9 August 117), was Roman Emperor from 98 to 117 AD. Born into a non-patrician family in the province of Hispania Baetica, Trajan rose to prominence during the reign of emperor Domitian. Serving as a legatus legionis in Hispania Tarraconensis, in 89 Trajan supported the emperor against a revolt on the Rhine led by Antonius Saturninus.

In September 96, Domitian was succeeded by Marcus Cocceius Nerva, an old and childless senator who proved to be unpopular with the army. After a brief and tumultuous year in power, a revolt by members of the Praetorian Guard compelled him to adopt the more popular Trajan as his heir and successor. Nerva died on 27 January 98, and was succeeded by his adopted son without incident.

As a civilian administrator, Trajan is best known for his extensive public building program which reshaped the city of Rome and left multiple enduring landmarks such as Trajan's Forum, Trajan's Market and Trajan's Column. Early in his reign, he annexed the Nabataean kingdom, creating the province of Arabia Petraea. His conquest of Dacia enriched the empire greatly — the new province possessed many valuable gold mines.