The wall at 1st Avenue and Seneca is a retaining wall. Built to prevent the ground supporting the roadway from sliding down the hill towards the sea as it is want to do once the trees and their roots that were anchoring the ground were removed.
This whole area is filled with retaining walls. They are the only way to get buildings to rub up against the steep inclines.
I'm not au fait with the drawing tools in gimp but these grey dots are examples of the same walls.
These grey lines show where the retaining walls run.
The slope below the dot on the right is much steeper than the slope above it as evidenced by the trees position. This means that in that image the hill is running down right to left as we look at it and from back to front as we look at it. The steepness of the right to left is shallow compared with the steepness running back to front.
Whatever that thing below is, I don’t know, could be a bunch of piles
Been here before as I recall in this thread.
The area illustrates the problems and the probable reason for the retaining walls being so massive.
First is your positioning of the diller in the blue box and the lower one is my clumsy paint by numbers effort which illustrates what I mean,
The red line shows a natural cut or edge in the land. It has no man made supports it is just the natural 'cliff edge'.
The yellow line shows a wooden jetty made of tree trunk piles sunk into the shallows to create a level running bed for a railway.
The blue line shows a wooden piled jetty that has been back filled to create flat solid land within it.
The green line shows the Front street regrading at the point where it crosses what used to be a ravine. It is either wooden piling or brick walling.
The sloping land on the upside is a way to prevent further slippage of the upper land onto the new street,
This week’s feature on First Avenue, like last week’s on Third, looks north from Seneca Street, here a few yards south of Seneca. Imagine, if you will, in place of Seneca, a ravine. Following the 1852-3 pioneer settlement on the east side of Elliott Bay, a bridge was eventually needed to cross this gully that broke through the waterfront bluff. The Native Americans had favored the eroded cut as suitable for burials, and during pioneer days bodies were still exposed during heavy rains. In 1876 the bridge over the ravine was reinforced with a log retaining wall during the regrading of Front Street (First Avenue) from Mill Street (Yesler Way) to Pike Street. It was Seattle’s first oversized public work.
So they went from natural to log piling to brick in that area.
I do not know the veracity of the content quoted here but I include the photograph as it shows the underlying ground and the problems of building on such ground.
The intersection of Seneca and Front Street (no.5) photographed from a waterfront rebuilding after the Great Fire of June 6, 1889. The 1888 map shows a few fire-destroyed subjects including the Cracker factory (3) and the electric generating plant (4) to either side of Seneca and just west of Front/First.
Again no way to establish the veracity of the content quoted.
The best survivor here is the most distant one, the Diller Hotel at the southeast corner of University and First. A heavy cornice, since removed as an earthquake precaution, tops its four floors. The Diller developed into a popular hangout for political and fraternal huddling. Named for its builder’s family – the family home had been on the corner – the Diller was conceived before the Great Fire and built soon after of Japanese bricks. Understandably, bricks were then hard to come by.
So the hotel was up by 1890. Here it is in about 1909 with the building that would become Herbs store. The wall in the op photo is off to the right just out of shot. However I include this image as it shows the two slopes of the streets and their differing steepness. I really struggle with this grid street layout system so if I butcher it come in and correct me, please. First avenue is running right to left in the photograph ans is at a much shallower angle than University Street which is at right angles to it. The Diller is actually built on flat land as in a terrace created by the construction of the Front Street/First Avenue regrading as we see quote clearly in the photograph.
My suggestion is the roadway that is first Avenue today and Front Street back then and the land the Diller and all the buildings on the up side of the road are only there thanks to the hidden brick retaining wall.
I suggest these railings likely
Became this
Then became this.
Here is a photo of the Seneca Hotel from 19266 which I feel answers the op photo conundrum. I stress this is MY feeling!
As we see
below above the footpath changes from concrete/paving to boardwalk right at the point of the lamppost. This suggests to me the actual retaining wall for the roadway is right underneath the gutter of the road and its kerb. The reason for the change in materials is the boardwalk is in mid air with nothing underneath it as we can see though the railings the hotel building carries on down and the railings sequence above shows the overhanging footpath extending beyond the retaining wall.
We also see the footpath is at an angle in relation to the hotel front so to accommodate the inclined footpath the hotel builders stepped their entrances up/down accordingly.
The wall of the hotel facing the street but below street level was used along with the hidden retaining wall to provide a solid 'tray' or support for a more substantial and durable footpath hence the change in material being right where the lamppost stands and most importantly the hotel building ends.
What we see in the op colour photograph is the remains of the hotel building left up to support the footpath. The cutouts in the walls are openings to allow the operators of the stores and or the hotel to have cellar facilities or 'free storage rooms' or even unlicensed accommodation or given the times of prohibition hidden liquor storage (speculation obviously) between the two walls.
Once the blue painted wall is removed I feel pretty certain we would see a brick retaining wall behind it that holds the First Avenue roadway in place.
The pale blue car is abutting the kerb of the road. Between it and the security fencing there is enough room on the footpath for the car door to open and people to get in and out as evidenced by the height of the ground the man in front of the beige car is standing on. Between the fencing and where we see where the joists/supports are resting on the wall is the remainder of the footpath. The wall we see bearing the remains of blue paint/plaster and holding the joists is the remains of the Hotel Seneca.
I went looking for the demolition date for the Hotel Seneca as its clear from the content of the colour photo that it is ongoing at the time the photo was taken. Sadly neither tineye or google reverse image search was any use and asking multiple search engines the question simply brings up loads of links that are unrelated.
This however did turn up which gives some idea of what is normally hidden from view. I cannot go direct to the linked page, legla reason in my region apparently, but you American folks can!
