anyone know anything about it
ie how long does/can it last?
I know of people who have suffered. Essentially, it is caused by nervous stress, so it is not a physical condition, but rather a psychological condition brought on by excessive tension and fear. It is treatable, though. 
Feel free to PM me if you want further information.
Whilst I can see what you are trying to explain, you are wrong.
Agoraphobia, just like any irrational fear can be brought on by anything from Alcohol or Drug miss-use to a traumatic experience not connected to the Phobia.
I've been actively helping sufferers of Panic, Anxiety and Phobia's since I developed and conquered Agora, I have advised so called 'specialists' on how to assist sufferers and the website I contribute to has NHS accreditation.
MantaGTE, if you or someone you know is beginning to fel the effects of Agora, please do not hesitate to contact me. I'll give you my personal telephone number and put you in contact with a genuine online support group who can then (if required) direct you to a local source of inspiration.