Istanbul Museum of the History of Science and Technology in Islam

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.

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.

It has a sandy beach backed by forest where a creek runs out. This is as far as you can go in a standard car.

Feshane began as a factory producing fezzes (fes), the red hats made of felt adopted by the Ottomans in the early 19th century as a part of westernizing efforts in lieu of much more traditional turbans. However, the fez was scrapped in favour of western garments during Atatürk's reforms of the 1920s and 30s as it was thought to symbolize the old, decidedly oriental regime. A restoration in 1998 made it a cultural and exhibition center, and after another in 2023, it was reopened as a culture and art center under the name Artistanbul Feshane.

A Byzantine monastery complex carved into a cliff, set in a lush valley. The site is free, but May-Sept there's a 32 TL toll for cars on the access roads. There's a picnic area, pity about all the trash, and a couple of restaurants nearby.

This was rediscovered in 2010 when an overlying building was demolished. It was built circa 430 AD to store water brought in by Valens Aqueduct. It's smaller than the better-known Basilica Cistern, but better lit, more atmospheric and less touristy.

A remarkable Bulgarian Orthodox church better known as Demir Kilise, "Iron Church", as it's a cast iron prefab. The Bulgarians split from the Greek Orthodox and established their own wooden church in 1870, which burned down. The ground was too weak for a masonry or concrete structure so they opted for cast iron. The sections were cast in Vienna, shipped here and assembled, to open in 1898. The church was renovated in 2018, but the archpatriarchate building across the street remains a gaunt shell.

The "Polish village" was founded in 1842 by Polish settlers in the wake of the failed uprising against Russian Imperial rule, and reinforced by more settlers after every subsequent civil upheaval until Poland's independence in 1918. Most then returned, but several stayed on, adopting Turkish citizenship but maintaining their Polish language and culture. The village has houses in traditional Polish style, a 1914 little Catholic chapel, and the Church of Matka Boska Częstochowska. It's set in woodland (a nature park) and is a popular day-trip from the city. There's four restaurants and half a dozen small hotels, plus more of each in nearby Beykoz.

A village with an impressive citadel overlooking the Bosphorus and its mouth into the Black Sea. By land it's accessible only by a hairpinning road through the forest, with few buses. It's best reached by ferry from Eminönü (twice daily) or Sariyer (frequent). In the village, a road is signposted up to the hilltop Yoros citadel (a little more than 1 km, 20 min on foot, free admission). There's a pleasant area with cafés by the ferry pier; the place gets crowded at weekends during summer. Nasty big dogs stalk the citadel area at night. See Istanbul#The_classic_Bosphorus_cruise.

Built circa 1200 as the Eastern Orthodox Theotokos Kyriotissa Church, after the Ottoman conquest it was handed over to the Qalandari, a Sufi sect. In the mid-18th century it was converted to a Sunni mosque, and its mosaics were plastered over. The original appearance was restored in the 1970s.

The Greek Orthodox church is on the highest summit of the archipelago, Yücetepe ("great hill") at 203 m asl. Walk up from Birlik Meydanı for about 35-40 min; the cobbled incline is too steep for a bicycle. The church building is unexceptional, but the backyard has a great view of the other islands and the sea. St George's day is celebrated here annually on Apr 23, when you can expect tens of thousands attendees willing to make wishes — if you want to skip the crowds set off before 06:00 or else you will be standing for a long time until you are let inside by the police in groups of 10–15 people at once. Wishmaking rituals range from usual candle burning, to slightly more unusual climbing up to the church on bare feet, to very curious untying wool balls all along the path leading there. If you are interested to partake, you will meet lots of vendors selling candles on the streets that day, right as soon as you step out of the ferry, but it's best to have them from the church for a donation. In case you are wondering if all of Turkey's dwindled Greek Orthodox minority are there that day, or if the community is even that populous, no, most of the visitors eagerly waiting for a blessing from the priest are non-Christian Turks, but there is nothing surprising about that: this is Turkey, where the east and the west meet, and cultures truly mix.

If you are already in the area, it's worth considering to visit this waterside neo-Baroque manor, built in the 19th century for the countryside and hunting excursions of the Ottoman dynasty. The area, where the Göksu River flows into the Bosphorus, was known as "the Sweet Waters of Asia" by the pioneer European travellers of the epoch (as opposed to "the Sweet Waters of Europe", another contemporary elite recreational area on the other side of the city, where the Kağıthane and Alibeyköy Rivers empty into the Golden Horn).

This building dating back to 1945 houses the local radio branch of the state radio and television corporation of Turkey (TRT). Not exactly an architectural pearl (although fans of the 1940s' totalitarian architecture will likely find its stately façade interesting), but it is prominent for the part it played in the political history of Turkey: It was occupied three times by the Army, in 1960, 1971, and most recently in 1980, when the radio was decidedly the broadcast type ranging most wide and far, to announce that they had launched a coup and taken over the governance of the country.

Istanbul's former Asia-side railway station nowadays has no trains, but is worth a look. It was built by the Germans in 1908 in a distinctive Teutonic-castle style - to make an impact on travellers from Asia about to step into Europe, and a counterpoint to Sirkeci station (also closed) on the European side which is modelled in Oriental style. It's intended eventually to make this the terminus for the high speed rail network.

This is an industry museum showcasing the evolution of machines. Many transport related items including a submarine, classic cars, railway carriages, an out-of-service Bosphorus ferry and a Douglas DC-3 aircraft (possible to board) are on display, among others. Also houses a typical Istanbul streetscape with its shops and all as how it would look in the past.

Completed in 1851, this houses a mantle said to have been worn by the prophet Muhammad. The mantle is displayed during Ramadan.

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.

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.

Situated on the gentle hill overlooking the neighbourhood of Emirgan and the Bosphorus, Emirgan Park was for long the only place in the city where Istanbulites can admire the beauty of tulips. Having lost that distinction since the first decade of the 2000s as tulips are now everywhere, this is still a beautiful park with artificial ponds, small waterfalls, and impressive views of the Bosphorus. There are also cafes with open-air sections housed in pleasant former imperial hunting manors. Squirrels are there, too, in the middle of this metropolis of more than 15 million people, though you may have to look a bit deeper (or a bit upper on the branches!) to spot them.