The M building hosted all conferences during the renovation of the C building (previously the main conference facility) from 2009-2013. Both M and C buildings are now being used for meetings. Very large conferences can be accommodated in the neighbouring Austria Center Vienna (ACV), a separate conference and exhibition centre with a capacity of 6,000, which is with the VIC campus part of the UNO-City. The ACV has an indoor link to the VIC buildings. It is guarded by United Nations security personnel, since the VIC has exterritorial status; the ACV does not.