Large bed: article carried by everyone round building (6,4)

'building' is the definition.
(I know that Albert Hall is a rotunda)

'large bed article carried by everyone' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'bed' becomes 'berth' (berth is a kind of bed).
'article' becomes 'a' (the indefinite article in English).
'carried by' is a charade indicator (letters next to each other) (in a down clue, some letters hold up others).
'everyone' becomes 'all' (all people).
'l'+'berth'='lberth'
'lberth' after 'a' is 'alberth'.
'alberth'+'all'='ALBERT HALL'

'round' acts as a link.