widow's walk
Concise Oxford English Dictionary © 2008 Oxford University Press:
widow's walk
▶noun N. Amer. a railed or balustraded platform built on a roof in early New England houses, providing an unimpeded view of the sea.
– origin 1930s: with ref. to its use as a viewpoint for return of a seafaring husband.
'widow's walk' also found in these Oxford entries:

