Abu Dhabi

Abu Dhabi is the richest city in the world. It has 9% of the proven oil reserves in the entire world.  The emirate produces 93% of the oil from the UAE, and it generates 56% of the GDP of the UAE.  It has a nominal GDP of 911 billion dirhams/year ($248 billion).  The city only has 921,000 people.  You do the math.

Dubai has the flash but Abu Dhabi has the cash. Furthermore, the ruler of Abu Dhabi is always the president of the UAE and the capital of the UAE is in Abu Dhabi.

The Abu Dhabi Investment Authority may have as much as $875 billion in assets.  It is the largest sovereign wealth fund in the world and consistently generates returns of of over 7%.