What lights are used on top of a building or structure near an airport?
The general guidelines are:


  4.3 Lighting Systems. Obstruction lighting may be displayed on structures as follows:
  
  
  Aviation Red Obstruction Lights. Use flashing lights and/or steady-burning lights during nighttime. Tower structures are typically
  marked with flashing red lights. Buildings and smaller obstructions
  located near airports should be marked with steady-burning red lights.
  (See Chapter 5).
  Medium-Intensity Flashing White Obstruction Lights. Medium-intensity flashing white obstruction lights may be used during
  daytime and twilight with automatically selected reduced intensity for
  nighttime operation. When this system is used on structures 700 feet
  (213 m) AGL or less, other methods of marking and lighting the
  structure may be omitted. Aviation orange and white paint is always
  required for daytime marking on structures exceeding 700 feet (213 m)
  AGL. This system is not normally recommended on structures 200 feet
  (61 m) AGL or less.
  High-Intensity Flashing White Obstruction Lights. High-intensity flashing white obstruction lights may be used during daytime with
  automatically selected reduced intensities for twilight and nighttime
  operations. When this system is used, other methods of marking and
  lighting the structure may be omitted. This system should not be used
  on structures 700 feet (213 m) AGL or less, unless an FAA aeronautical
  study shows otherwise.
  Note: All flashing lights on a structure
  should flash simultaneously except for catenary support structures,
  which have a distinct flashing sequence between the levels of lights
  (see paragraph 4.4).
  Dual Lighting. This system consists of red lights for nighttime and high- or medium-intensity flashing white obstruction lights for
  daytime and twilight. When a dual lighting system incorporates
  medium-intensity flashing white lights on structures 700 feet (213 m)
  AGL or less or high-intensity flashing white lights on structures
  greater than 700 feet (213 m) AGL, other methods of marking the
  structure may be omitted.  
  


Specific details are spelled out in AC 70/7460-1L CHG1 Obstruction Marking and Lighting.