By Taxi
On the airport (T1 and T2) or central bus station there is a desk of OK Supertrance taxi (http://www.oktaxi.net/offices_en.php) where you could order a taxi.
Other Taxi Companies:
By Bus
Nearby NSA pass buses № 94, 102, 280, 294.
By Metro
From metro station G. M. Dimitrov you have to take bus 280 or 294 to their last bus stop – National Sports Academy (Direction Sofia University – SK of NSA).
Important links:
Metropoliten Sofia: http://www2.metropolitan.bg/en/map/
Public transport in Sofia: http://www.sofiatraffic.bg/en/