I've been looking at pictures of this modern fish bowl--a cool upgrade to an old standby. Found a few pics that help illustrate the size: scale's tricky without a decent reference point.
Tank comes in both white or black & can be stacked:
I was worried about how these bowls would stack without smothering the fish? But the top 'windows' are open--so when stacked, the surface of water sets well below these windows, & your fish get plenty of healthy air flow.
For another great size shot, here's a stack of small, mass-market paperbacks next to the 'hotel.' Quite a small container--I wouldn't want more than a couple small fish in there so they wouldn't be crowded.
I've seen some fish hotels with pretty rocks and some aquatic plants in them--looks nice and seems like a healthy environment. If you chose your little fish carefully so they were the right size, it would be a fab flat for your goldfish friends.