Asgard
From Tardis Wiki, the free Doctor Who reference
Asgard was a location where the Doctor and River Song had shared a picnic. (DW: Silence in the Library)
As seen in DW: The Impossible Astronaut we now know that this is a reference to the picnic the Doctor shared with River, Amy and Rory in the Valley of the Gods before he is given a viking funeral in the lake.
