- The neighborhood around Harlequin Park in New Orleans has streets named after gemstones.  That neighborhood is too far north, however, to have a latitude starting with "29."  (See image 7 for more info.)

- "Jewels" could also refer to the beads tossed during Mardi Gras parades.

- The John Minor Wisdom United States Court of Appeals Building across Camp Street from Lafayette Square has 15 rows of stonework on first floor.  

- There are many old buildings around Lafayette Square that have stone steps going down to the street level, but we don't yet have a list of which ones (if any) have 15 rows of steps.

In the middle of twenty-one

From end to end

- This could refer to the three statues in Lafayette Square.  John McDonogh is at the west end, Benjamin Franklin is at the east end, and Henry Clay in the center of the park.

As the sound of friends

Fills the afternoon hours

Illustration in Ballou's Pictorial, via [1], Public Domain,

https://commons.wikimedia.org/w/index.php?curid=16520066

Here is a sovereign people

Who build palaces to shelter

Their heads for a night!

- This line originally appeared in  Travels in the United States in 1847 by Domingo Faustino Sarmiento of Argentina, when the author was describing a hotel in New Orleans:

"The Saint Charles, which lifted its proud head above the surrounding hills and woods, the Saint Charles, which had called up my memory of Saint Peter's in Rome, was no more than a hotel! Here is the sovereign people who build palaces to shelter their heads for a night! Here is the religion which is dedicated to man as man, and here the marvels of art are lavished on the glorification of the masses." 

The line was reprinted as an excerpt in Abroad in America: visitors to the new nation, 1776-1914, edited by Marc Pachter and Frances Stevenson Wein and published in 1976.  (We can assume that Preiss saw the reprinted quote, rather than the original, because he used another quotation from Abroad in America as a clue in Verse 6.)

- The hotel Sarmiento was describing was the St. Charles. The hotel is described this way in New Orleans: A Pictorial History, by Leonard Victor Huber:

"The St. Charles was the most admired building in the New Orleans of the 1840s.  Named for the street on which it stood, this 350-room caravansary, with its huge barroom adorned with a range of Ionic columns and its stately ballroom above it, became the center of business and social life in the American section of the city.  The first St. Charles was surmounted by a cupola and dome 46 feet in diameter, which, with its lantern, rose to a height of 185 feet above street level.  The dome of the St. Charles was visible for miles, and guests of the hotel who cared to climb to the colonnade and porch, which supported the dome, could get a fine view of the city and the winding Mississippi.  ...  Fire, which broke out on January 18, 1851, in the St. Charles's upper stories soon went out of control due to poor fire-fighting equipment and consumed the hotel, the Verandah Hotel across the street, and continued up St. Charles Street all the way to Lafayette Street, destroying fifteen buildings, including Dr. Clapp's Strangers' Church."

- The St. Charles Hotel (now called the Royal St. Charles) is located at the corner of St. Charles Avenue and Common Street.  A pedestrian traveling between Lafayette Square and St. Louis Cathedral would pass the site of the St. Charles Hotel along the way.  (Lafayette Square is on St. Charles Avenue and the cathedral is on Royal Street.  St. Charles Avenue turns into Royal Street when it crosses Canal Street.)

Gnomes admire

Fays delight

The namesakes meeting

Near this site.

- Lafayette Street and Lafayette Square meet at the square.

- Is there a place where two streets named "Gnome" and "Fay" intersect?  Or could it be people named after those words?

- I believe I know the location of this site. I'm not going to go look for the treasure, but if someone does and it's there, please let me know.  

There's a statue in a little triangle of land bordered by N. Conti St, Decatur and N. Peters.  Within this space is a statue known as the Bienville Monument Historical Marker. The statue has Bienville (founder of New Orleans), a Native American Indian and a Monk or Brother (?).  So the line goes:

Gnomes admired (Gnomes are Earth Dwellers, as are Native American Indians)

Fays delight (Fay is a reference to Faith, hence the Monk/Brother)

The namesakes meeting near this site.  (Bienville named the city:

Nouvelle-Orleans)

This is the site where all three of these are featured on the same statue.  Which also goes back to the line about three standing guard.  If you look at a map of this location on a map of New Orleans, you will see it lies on the crescent of the Mississippi River, as in the image.  Also: if you look at the hand in the image, the two fingers at the top, form a triangle.  I believe the image of the animal to the left, in the border is a dragon, once used on the French Flags.  All the other places mentioned in other comments, are all around this location.   I don't know where it could be within that area.  But, I know it's very close to the river and I'm not sure if it was flooded during Katrina or not.  I hope someone looks for it there.  

- By looking at image 9, we can connect the painting to the roof of Trafalgar school. Trafalgar School is located near Percy Walters Park in Montreal, where there is a sign that points toward Docteur Penfield Avenue. The sign is diamond shaped (jewels).

- From the top tip to the bottom tip there are 15 diamonds that line the far right edge.

- Also at Percy Walters Park are a series of 21 fence panels along the Rue Redpath side. Each panel of fence has 15 bars that go down to the ground.

In the middle of twenty-one

From end to end

Only three stand watch

- Avenue Docteur Penfield is a 21 letter word. Percy Walters Park is located in the centre of the street.

- This could refer to the 3 signs with dogs on them which are located at every entrance to the park - watchdogs.

- On Rue Redpath there are 21 panels of fences. Each panel of fence has 15 bars that go down to the ground. The central panel could possibly have the casque burried underneath.

- Perhaps a reference to the “Three Bares” fountain outside the Redpath museum at the north end of the

avenue.

As the sound of friends

Fills the afternoon hours

- The Three Bares are located at Redpath Museum Avenue Docteur Penfieldon.

- Rue Redpath on the side of the park.

Here is a sovereign people

Who build palaces to shelter

Their heads for a night!

- Albert Prince of Wales once stayed in Montreal near the park.

- This could also refer to the Quebecois desire to become a sovereign state, as seen in the 1980 referendum.

Gnomes admire

Fays delight

The namesakes meeting

Near this site.

- The “namesakes” might be the Three Bares, named after the Three Bears, who meet at Redpath, one of

the roads bordering the park.

- Alternatively, the “namesakes” might be “gnomes of Zurich”, or bankers, who met at the Mount

Stephen Club (the residence of banker George Stephen). 

- Another thing that would lead us to believe the location is in Montreal is the fact that the meaning of Montreal is Mount Royal. Percy Walters Park is located at the base of Mount Royal.

- Refers to the Sunlife Building which borders Dorchester Sq on Metcalfe St. It is well known that during WWII the British Crown Jewels as well as gold reserves for several European countries were stored here for safekeeping.

- While the Sunlife Building is in fact 26 stories tall, you can only count 15 rows down to the ground, where you would be standing.  See pic: http://imgur.com/W3RPt2v  

In the middle of twenty-one 

From end to end

- Again, Sunlife.  When you stand at the entrance to the building (facing Dorchester Sq), you are standing in the middle 21 columns of windows.  (There are actual Romanesque columns on the building, but they do not run "from end to end").  

The columns of windows do run from end to end. (Notice we are counting rows of squares when counting the 15 rows and 21 columns.  This may be why checkerboards are stressed in Image 9).

- There are only three human statues in Dorchester Square: Prime Minister Laurier, Scottish poet Robbie Burns, and the soldier restraining his horse on the Boer War Monument. 

As the sound of friends

Fills the afternoon hours 

Here is a sovereign people

Who build palaces to shelter

Their heads for a night! 

- Windsor Hotel, located on Peel St. opposite the Sunlife Building, which also borders Dorchester Sq.  The name of Windsor is sovereign as the House of Windsor is the royal house of the UK as well as the Commonwealth (including Canada).  The Windsor Hotel itself was lavish and enormous (palatial) before 1957 when it was extensively damaged.  It was literally a host to royalty, King George VI and Elizabeth famously stayed here on their royal tour in 1939.  The term "sovereign people" can also signify the Square's former name of Dominion Square, as dominion means "sovereignty or the territory of a sovereign or government"

Gnomes admire

Fays delight 

- General knowledge says gnomes live in gardens, fairies live in trees.  This is not a specific statement.  

There are trees and a flower bed in Dorchester Sq. Old pictures show there has always been a large ring shaped flower bed around the Boer War Monument. 

The namesakes meeting

Near this site. 

- Namesakes of Windsor?  There is a Victoria fountain in Dorchester Sq.  

Queen Victoria was a member of the House of Windsor.  She had the name before the Hotel Windsor was built, so is the hotel her namesake?  Again, Dorchester was called Dominion Square in 1980.  Possibly he is referring to how Windsor is a namesake of Dominion. It might not be important.  

The poem seems to point to Dorchester Sq, and even gives a general line to follow (the front entrance of the Sunlife).  

If you follow that line across the park, it will lead you across the Boer War Monument and on to the Windsor.  

The precise location on where to dig may be given by the "X" diagram at H7 on Image 9, as that symbol has not led to a physical location thus far.  It seems to read PX7.  This may refer to the shape of the paths in Dorchester Sq., the "P"

may stand for pillar (on the Sunlife building).  "P" may stand for Peel Street.