The small but opulently furnished Beylerbeyi Palace (millisaraylar.gov.tr; adult.student/child under 7 ₺800/200/free) is nestled under the Bosphorus Bridge in the suburb of Beylerbeyi, a short distance north of Üsküdar. Designed by Sarkis Balyan, brother of Nikoğos (architect of Dolmabahçe Palace), it delighted both Sultan Abdül Aziz (r 1861–76), who commissioned it, and the many foreign dignitaries who stayed here as the sultan's houseguests. Its last imperial "guest" was former Sultan Abdül Hamit II, who spent the last five years of his life under house arrest here.
An informative audio tour is included in the ticket price, but you'll need to leave ID as surety. As you explore the grand Selamlık (ceremonial quarters) and the small but opulent Harem in the main building, you'll pass through rooms decorated with frescoes of naval scenes, Bohemian crystal chandeliers, Ming vases and sumptuous Hereke carpets. Highlights include the downstairs hall with the huge marble pool used for cooling during summer, the elaborately painted and gilded sultan's apartment, and the wood-paneled sultan's audience room with its Baccarat chandelier, Hereke carpet and magnificent Bosphorus view. The other buildings in the palace compound, including the whimsical tent-like marble bathing pavilions by the water's edge, are closed to the public.
Note that the palace is closed on Mondays and that interior photography is prohibited. The most enjoyable way to get here is to take a ferry to Üsküdar and connect with the Üsküdar–Anadolu Kavağı ferry, which has Beylerbeyi as its first stop. Alternatively, take a bus from the bus station opposite the Dentur İskelesi in Üsküdar.