Things to do in Istanbul

Theme parks

Vialand
Entertainment park.

Miniaturk
Models of 1/25 scales of famous and historical buildings.

Aquariums

Istanbul Aquarium -- Sea Life Aquarium -- Dolphinarium

Speciality Museums

Rahmi M. Koc Museum
Collections of the industrial and engineering objects, models toys, dioramas

Historical places

Palaces, Mosques, Monuments , Mansions & Pavilions, Towers & fortress, Churches ... :

Topkapi Palace -- Dolmabahce Palace

Blue Mosque

Galata Tower

Basilica Cistern -- 1001 Columns Cistern

Column of Constantin -- Theodosius Obelisk

All historical places