2 The burden against the Valley of Vision. What ails you now, that you have all gone up to the housetops,
ESV - 1 The oracle concerning the valley of vision. What do you mean that you have gone up, all of you, to the housetops.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
I believe it is symbolic; it's a symbolic name generally understood to signify Jerusalem as being the home of prophetic vision (Isaiah 22:1,5).