The Maimoon Palace or Istana Maimun is a royal palace of Sultanete of Deli and also a well-known landmark in Medan, the capital city of North Sumatra, Indonesia. It is located at Jalan Brigjen Jenderal Katamso in downtown Medan. It is a huge palace with 40 rooms and covers an area of 2,772 m2, including the surrounding grounds. It was build on the order of Sultan Makmun Al Rasyid Perkasa Alamsyah, Sultan of Deli, in 1887 to 1891. Descendents of the Sultan still occupy a wing of the Palace.

The interior design of the palace is the most attractive part. It is a unique mixture of elements of the Malay cultural heritage as well as Italian, Spanish, Indian and Islam style. At that time it was a bold combination of traditional Malay and Islam styles and European styles. Some of the building materials were even imported from Europe.

Inside are family photographs, old weapons and furniture.

The Palace consists of two floors divided each into three parts: the main building, the left wing and the right weng. Each floor has 20 rooms. The total of 40 rooms of this Palace does not include the prison in the basement, kitchen and bathrooms.