Answer:

skylit

Answer	Crossword Clue
SKYLIT	Having horizontal windows
SKYLIT	Like an atrium
SKYLIT	Illuminated from above, perhaps

SKYLIT	Having natural illumination
SKYLIT	Naturally bright
SKYLIT	Illuminated naturally
SKYLIT	Like atria
SKYLIT	Like some lobbies
SKYLIT	Having a glass-fitted roof opening
SKYLIT	Like many an atrium