Actually it's a 'simple beam bridge' one post above, but on acid it wouldn't matter - it could look like a spongy, wavy, snake on stilts ;-)
Yeah, I reckon that bridge would be pretty amazing on acid! Next time I'm in Scotland I may take a trip to the Forth Rail Bridge. It's amazing when straight anyway; a stunning piece of Victorian engineering. Only problem is getting there!
As for "fun" things, that would depend on many variables. If taking a high dose of something then it would tend to be at home with music. I live next to some woods so I can escape if need be, but I tend to need to know that my bed and familiar surroundings are there if things become tense.
At lower doses, I like to just walk and see where my feet take me.
It's also substance dependent (possibly taking liberties here as the substance wasn't specified in the title); something like metocin I will quite happily take at home (especially good for winter months as I find the tricks it plays with light to be wondrous) and just go with the flow.
For miprocin, I have to have a keyboard handy as I seem to just churn out endless reams of thoughts.
Thinking about it, there is a common theme: go with the flow. Something that may seem a good idea when you are straight may turn out to be dull and uninteresting when tripping. A simple towel could provide lots of interest whereas a so-called psychedelic artwork is boring. Psychedelics are, IMHO, about tapping into your own mind and therefore seeking out things that others may find interesting doesn't really work, simply because we are all so different.