I came accross this ! a Tower designed by Zaha Hadid,
http://www.e-architect.co.uk/egypt/nile_tower_cairo.htm
The article was published in 2012, however i have been seeing pictures floating the internet dating 2009 ! which means its not much such a new concept... but if this is indeed to take place ... one word ... :WOW
Now imagine if these actually ever come into existence ... HELL IMAGINE where would they be buillt ? do we even have space for it
check the article below (pictures are clickable below, they will expand if you click them)
The new Nile Tower is designed as a gracious volume that elegantly borders the Nile River in the heart of Cairo.
The main structural elements of this 70 storey hotel and apartment tower are concrete fin walls that rotate gently over the full height of the tower. The gradual rotation of the fin walls generates a wide selection of orientations for the hotel rooms and apartments. These fin walls are reflected on the external façade, giving the tower its dynamic appearance.
On the west side – overlooking the river - the tower bulges out at the upper floors to maximize the views from hotel rooms and apartments. On the east side the tower is pulled out as a triangle on the lower floors to offer maximum stability. These opposite extensions make the overall tower seemingly lean over towards the Nile.
While enhancing the perspective when looking up from the foot of the tower this geometry also makes the tower seem in motion. This seeming rotation is further enhanced by emphasizing the diagonals running along the north and south facades.
The façade geometry on the west façade culminates at the lower levels in a volume overhanging the road towards the river, housing the common program of the tower.
At the foot of the tower, the façade drapes down over the large column free space next to the tower footprint where it forms a continuous glass plaza.
A high quality contribution to the east bank of the Nile, The Nile Tower also forms a valuable addition to the skyline of Cairo.
Nile Tower Cairo - Building Information
Program: Hotel & apartment tower
Client: Living in Interiors
Area: 120,000 sqm
Residential: 60,000 sqm
Hotel: 35,000 sqm
Height: Tower - 300m
Architect: Zaha Hadid Architects
Design: Zaha Hadid with Patrik Schumacher
Project Architect: Joris Pauwels
Project Team: Feng Xu, Paulo Flores, Sharifah Alshalfan, Tariq Khayyat
Cairo Tower images / information from Zaha Hadid Architects
Nile Tower Cairo design : Zaha Hadid Architects 
The main structural elements of this 70 storey hotel and apartment tower are concrete fin walls that rotate gently over the full height of the tower. The gradual rotation of the fin walls generates a wide selection of orientations for the hotel rooms and apartments. These fin walls are reflected on the external façade, giving the tower its dynamic appearance.
On the west side – overlooking the river - the tower bulges out at the upper floors to maximize the views from hotel rooms and apartments. On the east side the tower is pulled out as a triangle on the lower floors to offer maximum stability. These opposite extensions make the overall tower seemingly lean over towards the Nile.
While enhancing the perspective when looking up from the foot of the tower this geometry also makes the tower seem in motion. This seeming rotation is further enhanced by emphasizing the diagonals running along the north and south facades.
The façade geometry on the west façade culminates at the lower levels in a volume overhanging the road towards the river, housing the common program of the tower.
At the foot of the tower, the façade drapes down over the large column free space next to the tower footprint where it forms a continuous glass plaza.
A high quality contribution to the east bank of the Nile, The Nile Tower also forms a valuable addition to the skyline of Cairo.
