A fairly close synonym is gazebo, a word of troy used a coup
years ago but did not define. A pavilion can be a similar
construction. Somewhat related is the widow's walk, a small
structure on roof top, with sheltered place to sit or stand,
with view of harbor.

For a picturte of a "widow's walk" see: (scroll down 1/3)
http://www.intandem.com/NewPrideSite/MD/Logs/Log13.html