How would you add whimsy to this door?

[AnyIdiot]

Photos pending.

This door is the focal point of my arch. No one uses it and there is a warehouse behind it. How can I make it look interesting on a tiny budget and very little artistic talent?

A couple of points:
The warehouse owner is fine with me doing stuff to it as long as I don’t ruin its structural integrity.

I can’t do anything about the fake grass, landlords choice.

I was going to suggest the same as Gatekeeper and Aparecium: make the most of the old wood and attach heavy ironwork to it, (pretend) hinges and door knob. Give it an a distressed finish or black paint. Make it look like a bit LOTR/hobbity.
Can you have climbing plants there if it's the end of your washing line? It doesn't sound practical.
Place a very large, focal-point pot in front of it, to match / echo the pots by the arch.

Thank you for all the ideas. I am feeling inspired now and can’t wait to get started. I will post a picture when it is done.

If it’s not your door then just paint it with whatever you have, plant a climber around it (clematis, jasmine) and put a focal point in front of it (bench, sun dial, bird table, full size replica of Michael angelo’s David?)

A mirror on the garden can be a fire risk, id just paint it, I like the 10 downing st idea

Love the no 10 Downing Street idea!

Failing that - if the door is never used could you put up some trellis on it and plant a climber?

How about disguising the door with a large, wide trellis and an evergreen climber of some sort (jasmine, clematis). Then in front add something else as the focal point, maybe a statue, raised bird bath, water feature or a little bistro table and chairs. I think having a door you can’t go through would feel a bit disappointing, better to have a focal point is worth going to. A patio fruit tree in a pot is something else you could do.

Or if you wanted to keep the door as a focal point, you can look on Pinterest or Instagram for folk doors, for some whimsical inspiration.

I think having a door you can’t go through would feel a bit disappointing
No, it's a classic gardening trick: it implies something beyond, gives an air of mystery and intrigue. Even better if it's half-hidden behind something like ivy (which would also hide the dreadful brickwork!)

But turning it into a seating area is a good idea because that corner looks like a sun-trap.

If door doesnt need to open out a trellis up, use your green paint.
Maybe seal that old door up first with yacht varnish so wood doesn't rot further.