Remove tree and confusing background clutter. Crop RH side. Paint sky w/ gradient. Leave section marker for Ferris Wheel.

Create Scarab side panel -
Paint stone scarab.
Use Bevel and Emboss layer styles to give 3d effect.
Use KPT Materializer filter for golden orb.

Paint Tut Magnet - Set Brush mode to "Vivid Light"
Image>Adjustments>Selective Color>Neutrals to give golden color.
Filter>Render>Lighting Effect to brighten top as if in sun.

Top sphynxes -
Extract sphynx image
Image>Adjustments>Selective Color>Neutrals>Increase yellow to tint image.
Image>Adjustments>Hue and Saturation>Increase saturation to intensify tint.

Mummy, Part 1 -
Extract mummy from background, remove eyes.
Duplicate image and create "sketch effect."
Create Merge Visible layer and place over Extracted Color layer and change mode to "Soft Light."

Mummy, Part 2 -
Duplicate eyes and mouth from GhostRide background image.
Place eyes on new layer beneath Mummy. Resize to match eye holes. With Magic wand on Mummy layer, select eye holes.
Invert selection, and remove excess from Eye layer.
Place Eye layer on top of Mummy, and paint edges to blend, and paint bandage accents.
Extract mouth, paint teeth to look yellowed and scummy, place on layer above mummy.
Create Merge Visible layer, and place over GhostTrain background layer. Reduce opacity, and use Eraser to remove areas where background sections show join gaps.

Extract Great Pyramid for top panel.
Duplicate and with polygonal lasso, outline edges and paint for placement next to Mummy.
Duplicate painted pyramid and paint with KPT Materializer to give gold reflective pattern.
Duplicate patterned pyramid 3 times. Resize and free transform to fit over ceiling spider web designs of background.

Nefertiti-
Duplicate image and extract Nefertiti.
With Airbrush tool at low opacity (16-26%) sample skin tones and paint to smooth out. Select areas with Lasso Tool and gaussian blur at 4-5 pixels to blend, deselect.
With paintbrush, paint in missing sections of ear on LH side. Select with Lasso tool, duplicate, flip horizontal and place on RH side, using paint brush to blend with image. Merge down.
Create new layer and paint over headress with blue. Change mode to vivid light and merge down. Use Clone stamp to fix areas of uneven color.
Select headband and on new layer, fill with gold color. Change mode to Soft LIght.
Select center decoration and change to gold with KPT Materializer filter.
Create new layer and paint colored sections of headpiece, and parts of neckace. Change mode to soft light and merge down.
Create new layer and fill with teal green color. Place under painted Nefertiti layer and merge.

Far Side Panel -
Select half of image with sun and pyramids. Crop. With rectangular marquee, select and copy pyramids to separate layer for use behind Mummy on other side of background.
Flip Sun and figure layer horizontal and resize to fit general side panel area on RH.
Create a selection of the panel, invert selection and trim excess from Sun and figure layer.
Reduce opacity and select shaded area with Polygonal Lassoo. Increase opacity to 100%, and darken selection with Image>Adjustments>Brightness and Contrast.
Reduce opacity to 56%, and use eraser to remove areas of railing and steps. (Not pictured - see final image)

Pyramids Painting -
Resize painting to fit background.
Select center of painting, and Free Transform to make pyramids taller and more visible. Crop excess.
Skew layer to fit into background, and increase saturation.
Darken layer.

Additional images -
Select and extract additional art for front panel, each to separate layers.
Increase saturation, Paint accent lines as needed, duplicate, resize, and skew to fit background image.

Signage-

From the Background image, duplicate the letter 'G' and paint out the letter, leaving the background.
Duplicate the background for all new letters that will be visible, and resize/skew the backgrounds to fit into the letter frames of the background.
With Type Tool, create the new letters and rasterize the type.
With the paintbrush, paint gray spots for the "sockets," and then with the same size brush, paint white over the top half to create the "light bulbs."
Resize and skew the letters to fit into the frames (see final image).

Ferris Wheel -
Crop Ferris image as close as possible. Flip Horizontal.
Paste onto Background image, resize to fit over "placeholder" area. Paint on background image to cover "Loose ends," so ferris wheel image fits.
There are too many fine lines, and this is my last element, so I didn't want to spend too long to adjust it. Using quick mask, I loosely painted areas to delete, inverting the selection.
For the remaining sky, use Image>Adjustments>Replace Color to change the sky. Select the sky color with the eydropper tool, and then increase the saturation, and change the hue and lightness "to taste."
Skew the image with the Free Transform tool to properly fit onto background image, erase the bottom edge, and use Filter>Blur More to soften the edges.

Putting it all together!
Repaint the background image as needed, and insert all of the manipulated elements.