Rumeli Fortress, also called Rumelihisarı, was built by Ottoman Sultan Mehmet II (aka the Conqueror) for the final siege of Constantinople. Its position on a bend in the Bosphorus, at its narrowest point, meant no ships could get in from or out of the city to the Black Sea. Construction began in April 1452 and lasted four months. Constantinople finally fell in April of the next year.
Under the Ottoman Empire, the fortress was used as a customs house and later a prison. In the nineteenth century, it was converted into housing. It remained a residential neighborhood until 1953, when President Celal Bayar relocated the residents and began extensive restorations.
Today the fortress serves as a museum. It's large and can be fun to explore. There are three large towers which offer great views of the Bosphorus and Asian Istanbul. The atmosphere is pleasant. During summer months it plays host to festivals and concerts. Several good restaurants are located just down the street. It's located just to the south of the Fatih Sultan Mehmet Bridge, one of two crossings of the Bosphorus. Getting here can be a bit tricky, though. It's only accessible by bus or car.
Location: Tarabya Yeniköy Cadde, Seriyer
Telephone: +90 0212 263 5305
Hours: Open Tuesday through Sunday 09:00-17:00.