Hagia Sophia in the past a Christian temple, then a mosque, from 1935 a museum, from 2020 a mosque.
Built in 537. A leading example of Byzantine architecture. Length 82 meters, width 73 meters, height 55 meters.

Topkapı Palace Museum opened in 1924.
Topkapı Palace was the residence of the Ottoman sultans. The construction of the palace began in 1459. Main parts of the palace: Imperial Gate, Four Courtyards, Harem, Imperial Treasury. Topkapı Palace covers an area of approximately 650,000 square meters.
The museum's collections include: Topkapı Dagger, Spoonmaker Diamond, religious relics, a collection of Ottoman and European weapons and armor, a collection of Chinese porcelain.

Opened in 2004, Istanbul Modern is managed by a private venture under the patronage of a non-profit foundation called İstanbul Modern Sanat Vakfı İstanbul Modern Sanat Müzesi İktisadi İşletmesi. In 2023, Istanbul Modern moved into the new building (https://www.museumworldranking.net/news/istanbul-modern-hosts-renzo-piano-the-architect-of-its-new-museum-building,168).
Istanbul Modern focuses on Turkish art from 1945 to the present day. Turkish artists whose works can be seen in the museum include: Fahrelnissa Zeid, Bedri Rami Eyüböglu, Semiha Berksoy, Adnan Çoker, Bedri Baykam, Selma Gurbüz, Yıldız Moran. Istanbul Modern also has in its collection works by international artists (some with Turkish roots) such as: Fahrelnissa Zeid, Yüksel Arslan, Tony Cragg, Nil Yalter, Anselm Kiefer, Olafur Eliasson, Gülsün Karamustafa, Sarkis, Laure Prouvost, and Refik Anadol.
Istanbul Modern has an area of 10,500 square meters.

Istanbul Modern, Photo by Enrico Cano, 2023