What is it?

[dermotcoll]

Hot Oil spout from a castle

[Roger]

Dermot, it is neither, but again you approach the target without hitting it.

[pmiller]

A scupper?

[Roger]

Not a scupper but related to a well known skipper. It is the bane of a man with one eye and one arm overlooking a square that is really a circle. There, I think I have given it away. Almost like transmitting in plain text.

[dolphus]

3d Model of Nelson's coat of arms ......

[ely862me]

door eye hole ?

[dale]

A fountain?

[chrisglasier]

@unknownuser said:

Roger Hawkins works from his base in Phoenix,Arizona, and accepts challenging design, photo and writing assignments from discriminating clients.

...and answers from wimps like us.

btw: Trafalgar Square is not circular.

[john.warburton]

Telescope support...?

[EarthMover]

Grate cover for a heating vent?

[john.warburton]

Musket firing port

[Daniel]

@roger said:

Not a scupper but related to a well known skipper. It is the bane of a man with one eye and one arm overlooking a square that is really a circle. There, I think I have given it away. Almost like transmitting in plain text.

Have something to do with Nelson's statue/column in Trafalger square?

[solo]

It's clearly a Sketchup model. that was too easy.

[watkins]

Well, that would be Horatio. Is it the scroll work at the top of the column, or decorative work on a ship? However, the bane of Horatio would be pigeons.

Regards,
Bob

[Roger]

My dear Watkins. I apologize for transposing the statue of King Charles the 1st with the all but invisible Horatio Nelson. But be that as it may, the bane of Nelson's statue are the pigeons, but the bane of Nelson himself was more feline than avian. Still matey methinks you are hot on the trail.

[Roger]

Meanwhile I struggle with the dolphins. Hint. This is another clue meant to both inform you and throw you off at the same time.

[john.warburton]

Well, feline - there are the lions around the base of the column;

...and dolphins - many in the fountains there.

[john.warburton]

...surely it is not a vent for the loo's...

...or an overflow outlet for the water features...

[Roger]

Lions no, but bronze tigers I will give you and dolphins too. Arty bronze she be. Near the water but has never has sailed the sea.

[Roger]

Maybe this will put you inTOUCH with the answer.

I thought this would be an easy model, but there was more detail than I imagined.