London building a large place to sleep everyone (6,4)

'london building' is the definition.

'a large place to sleep everyone' is the wordplay.
I cannot really see how this works, but
'a' is present in the answer.
'large' could be 'l' and 'l' is located in the answer.
'place' could be 'berth' ('berth' can be a synonym of 'place') and 'berth' is present in the answer.
'everyone' could be 'all' (I've seen this before) and 'all' is found in the answer.
No letters remain.
This may be the basis of clue (or it may be nonsense).