Anadoluhisarı ("Anatolian Castle") is a castle on the Asian side of the Bosphorus in Istanbul, Turkey. It was built by the Ottoman Sultan Mehmed the Conqueror in 1451, as part of his preparations for the siege of Constantinople. The castle was used to control the passage of ships through the Bosphorus, and to protect the city from attack from the sea. It is one of the oldest surviving Ottoman castles, and is considered to be one of the most important landmarks in Istanbul.

1. Location: Anadoluhisarı is situated on the Asian side of Istanbul, specifically in the neighborhood of Anadoluhisarı within the Beykoz district. It is positioned at the narrowest point of the Bosphorus Strait, where it connects the Black Sea and the Sea of Marmara.

2. History: The fortress was commissioned by the Ottoman Sultan Beyazıt I in 1395. Its construction was part of a defensive strategy to control and protect the strategic waterway of the Bosphorus. Anadoluhisarı was the first Ottoman fortress built on the Asian side of the Bosphorus.

3. Architectural Features: Anadoluhisarı showcases classic Ottoman military architecture. The fortress is characterized by its large, imposing walls made of stone and its cylindrical tower. It also includes inner courtyards, chambers, and ramparts. The architectural style of the fortress represents the early Ottoman period.

4. Purpose: Anadoluhisarı served as a defensive structure to control the movement of ships through the Bosphorus and to protect the city of Constantinople (present-day Istanbul) from potential naval threats. It played a crucial role in securing the Ottoman capital.

5. Visitor Experience: Anadoluhisarı is a popular attraction for visitors interested in history and architecture. The fortress offers panoramic views of the Bosphorus and the surrounding area. Visitors can explore the grounds, walk along the walls, and enjoy the serene atmosphere. The fortress also hosts events and exhibitions related to its history and the broader historical context of Istanbul.

6. Accessibility: Anadoluhisarı is accessible to the public, and visitors can reach it by various means of transportation, including private vehicles, public buses, or by taking a boat tour along the Bosphorus. It's advisable to check the fortress's official website or local tourist information for the most up-to-date visiting hours and accessibility information.

Please note that while the information provided here is accurate based on historical knowledge, it's always advisable to verify specific details and any recent updates regarding Anadoluhisarı before planning a visit.