The Theodosius Cistern came to light again in 2010 after the demolition of a building that had stood above it for centuries. Originally constructed around 430 AD, this ancient structure was designed to store water supplied by the Valens Aqueduct, a key part of Istanbul’s historic water system.
Although the Theodosius Cistern is not as large as the famous Basilica Cistern, it offers a unique atmosphere. The lighting inside is thoughtfully arranged, creating a dramatic and mysterious setting that highlights its historic columns and arches. Visitors often find the quieter surroundings more peaceful, as the site tends to attract fewer crowds than other, more popular landmarks.
Source - https://en.wikipedia.org/wiki/Theodosius_Cistern
Named after a 16th-century village, founded by Serbs deported from Belgrade when it fell to the Ottomans. The village was popular as a forest resort, but its inhabitants were resettled in the 19th century and it's now a bosky ruin. The forest is mostly primordial and deciduous, predominantly oak. It's dotted with ancient aqueducts and dams as this area was a water catchment for Constantinople / Istanbul, and has lots of walking jogging and cycling trails and picnic areas. The two main ways in are via Bahçeköy (near the Arboretum entrance) and Kemerburgaz (which has the best aqueducts). There's a small access toll. The forest is supposedly a protected area but is being encroached on by highways and suburbs: this is likely to get worse as the access route to Istanbul's new airport leads right through it.
An attractive stairway mixing the Neo-Baroque and early Art Nouveau styles, climbing up from Bankalar St towards the Galata Tower. It was built in the 1870s by Abraham Salomon Camondo, who belonged to a prominent Ottoman-Venetian Jewish family of financiers and philanthropists.
The defining image of Istanbul, dominating the skyline with its great dome and six minarets. Completed in 1617 for Sultan Ahmed I, it's still a working mosque, so dress appropriately and avoid prayer times. Enter via the courtyard on the SW side. You step (shoeless) into the blue-tiled prayer hall beneath the main dome and its semi-domes. The mihrab is of finely carved marble, well-lit, and the minbar (pulpit) next to it is visible from almost all parts.
The third and grandest of the churches on this site, completed in 537 AD. The 30-m diameter dome covers what was for over 1000 years the largest enclosed space in the world, only surpassed in 1520 by Seville cathedral. It used "pendentive" architecture to throw the dome's weight onto four stout pillars, a design that inspired many Eastern Orthodox churches and Ottoman mosques. It became a mosque after the Ottoman conquest in 1453, remaining so until 1931. It was then a museum until 2020 when it was again proclaimed a mosque. That means you must work around prayer times and dress appropriately.
A contemporary art museum in a building converted from an old power plant: 1914-built and coal-fired, this was the oldest in Istanbul and the Ottoman Empire. Part of the plant was kept in almost exact original condition and now serves as the "Energy Museum".
Built in 1564 by Mimar Sinan for Rüstem Pasha, Grand Vizier of Suleiman the Magnificent, this small mosque has an interior covered by beautiful Iznik pottery, then at its zenith.
Museum in a restored building that was the stables for Topkapı Palace. It exhibits various instruments for astronomy, clocks, pumps, weaponry and so on developed in Islamic realms down the centuries, but these are modern repro, and explanations of their context are skimpy. Islamic science and technology preceded that of Europe, as they insist, but they get the tone wrong, as if that was the triumphal culmination rather than the springboard for further advance.
Built in the early 5th century as a monastery dedicated to Saint Andrew the Apostle, in 766 it was the burial place of Saint Andrew of Crete and was later re-dedicated to him. It was rebuilt in the late 9th century and again in the 13th, then around 1490 converted into a mosque. From the 16th century it was occupied by the Dervishes, when the legend arose that a chain hung to a cypress tree in the courtyard was a truth diviner. The chain was swung between rival witnesses and the one it hit was telling the truth. The cypress stump is still standing.
A private museum with a large painting collection and archaeological collections of measurement units and tools used in Asia Minor since antiquity and faiences of Kütahya.
Sokollu Mehmet Pasha was the grand vizier and de facto ruler of the Ottoman Empire during its 16th century golden age. He commissioned this mosque, one of three in the city to bear his name, but the sloping site was a challenge. He hired the best, Mimar Sinan, who completed it in 979 AH / 1571 AD, with the slope resolved by a fronting courtyard above shops and a medrese. The interior has outstanding İznik blue tiles, and three fragments of the Black Stone (Hajar al-Aswad) of the Kaaba: above the main entrance, minbar and mihrab.
The imperial enclave of the Ottoman emperors for four centuries. Lavishly decorated, with exhibitions of fine craftmanship and four courts of increasing grandeur. The second court has the Harem and the State Treasury, housing a weaponry display. The third court has the Imperial Treasury, with Islamic and Christian relics. The views from the Fourth Court over the Bosphorus are spectacular. Reckon on spending several hours here and bring water as the museum kiosk is overpriced.
Built in first half of the 15th century, this is the large medieval castle under the Second Bosphorus Bridge. Its former name Boğazkesen (Turkish)/Laimokopia (Greek) means both "strait-blocker" and "throat-cutter" in both languages and denotes the reason of its building—to shut the supply routes from the Black Sea in the north into the slowly falling apart Byzantine Empire through the Bosphorus. Rumeli, literally "the Roman land", was the name of the European half of the Ottoman Empire, and as is usual with some other structures and villages along the Bosphorus, used as a prefix to differentiate Rumeli Hisarı from its counterpart in the Asian Side, the much smaller Anadolu Hisarı just across the Bosphorus.
One of the icons of the city is also called the Leander's Tower, on a Bosphorus islet off Salacak. The local myth ascribes its name to a princess, whose father wanted to protect her in this offshore tower from a prophecy that she would be killed by a snakebite on her birthday, but the snake found its way inside a basket of fruits — ironically a birthday present from her father — and you've probably already guessed the rest of the story. In actual timeline, it served as a defensive structure (there was a wall connecting it to the Asian mainland, and the Byzantines used to stretch a chain from here to the European mainland across the mouth of the Bosphorus to shut it to adversary shipping in times of conflict, but they didn't during the final Ottoman siege in 1453), as a customs and quarantine station, as a lighthouse, as a warehouse of various sorts of goods, and as a high-end restaurant before the last restoration finished in 2023 dedicated it as a museum. There is a light show viewable from the mainland every day at 21:00.
A medieval citadel on the Bosphorus at the mouth of the Göksu creek. It was built in the late 14th century to control (polite word for "choke off") shipping along the Bosphorus, which narrows to 660 m at this point. It worked in tandem with Rumeli Citadel, built some 50 years later on the European bank. It fell into disrepair but was restored in the 1990s. You can't go in, but it's a pleasant setting; the entire village is named Anadolu Hisarı after the fort and has many traditional wooden houses (yalı). Ferries along the Bosphorus call here.