The Ulucanlar Prison Museum (Turkish: Ulucanlar Cezaevi Müzesi) is a former state prison in Ankara, Turkey, that was converted into a prison museum following restoration by Altındağ Municipality. The museum was opened in 2011. It is the first museum of its kind in Turkey.

Ulucanlar Prison was established in 1925 in the Ulucanlar neighborhood of Altındağ district in Ankara, which had recently become the new capital of the Turkish Republic.

The facility was built as a military depot in 1923, on an area of 34,000 m² (370,000 sq ft). In its history, it was renamed several times and called "Cebeci Tevkifhanesi" (Cebeci Jail), "Cebeci Umumi Hapishanesi" (Cebeci Public Prison), "Cebeci Sivil Cezaevi" (Cebeci Civilian Prison), "Ankara Merkez Kapalı Cezaevi" (Ankara Central Closed Prison) and finally "Ulucanlar Merkez Kapalı Cezaevi" (Ulucanlar Central Closed Prison).

The correction and detention facilities in Turkey are officially categorized in three security level groups as closed (Turkish: kapalı), semi-open (Turkish: yarı açık) and open (Turkish: açık) prisons. Closed prisons are maximum security penitentiaries with external and internal control that hold violent prisoners and those judged most likely to escape. Semi-open prisons are medium security correctional institutions without external control but with only internal physical barriers that house prisoners bearing a moderate escape risk who also have a job. Open prisons are low security, work-oriented prison camps with no external control and internal physical barriers that hold inmates who are allowed to have limited interaction with the public. As of September 1999, the mixed-sex prison hosted 776 detainees and prisoners held in nineteen wards in the close and semi-open prison sections. The prison's healthcare facility had a capacity of forty beds.

Several prison riots broke out in July, September and December 1999. Ten inmates died and at least 28 were injured in the September riot while three men's wards and some of the women's wards were destroyed. At this time, an incomplete escape tunnel was discovered. Radio journalist Füsun Erdoğan was arrested while covering a press release regarding these events.

In 2006, the inmates of the closed prison section were transferred to a newly built prison in Sincan, Ankara. The evacuation of the semi-open prison section took place later.

During its 81-year existence, Ulucanlar Prison held notable intellectuals with different political views including journalists, poets, and writers, as well as professional politicians alongside political activists and criminals. Among the notable people who were detained or imprisoned (not including executions) were:

The prison was also the site of torture and cruelty as well as many prison riots and executions.