Modeling
I add a cylinder and rotate it around the X-Axis by 90-degrees
In Edit Mode, I delete the bottom half of the vertices
I select the bottom vertices and extrude them down along the Z-Axis
I select the vertices in the front and use SHIFT S to move the cursor to the selected vertices – this will help when I use the mirror modifier
In Object Mode, I select the object, right-click and under Set Origin menu, I choose Origin to 3D Cursor
I use CTRL A to apply all the transforms
To make the Mirror Modifier easier to control, I add an Empty
I select the arch and add a mirror modifier – using the Y-Axis and the Mirror Object is the Empty
I select the Empty and rotate it around the Z-Axis by 45-degrees
Back on the Mirror Modifier, I will use the Bisect option for the Y-Axis – this will cut the mesh across the mirror plane
I apply the Mirror Modifier
In Edit Mode, I delete the extraneous vertices
I also select the top-most vertex and use SHIFT S to move the 3D cursor to the selected vertex
In Object Mode, I right-click on the arch and under Set Origin menu, I choose Origin to 3D Cursor
I can hide the Empty and add another Mirror Modifier along the X- and Y-Axis
I also right-click on the arch and choose Shade Auto Smooth
I apply both Modifiers
UV & Materials
I split the Viewport and open the UV Editor and the Shader Editor
In Edit Mode, I select the Edges that connect each section and the front Edges for each individual section
I right-click and choose Mark Seams
I select the entire object and use the U-key to open the UV Mapping menu
Under the Unwrap submenu, I choose Conformal
I make a new UV Map and name it – I will use a 2K map size
I will be using a material I downloaded from Ambient CG
I will also be using the Node Wrangler Add-on
In Material Mode, I make a new material
I select the Principled Shader and, using CTRL SHIFT T, I open the textures for the material I downloaded
I can fine tune the textures
For example, I can increase the Scale on the Mapping Node
I can also lower the strength of the Normal and Displacement
If I want to change the color, I can add a Color Ramp between the Albedo and the Principled Shader
I change the Interpolation to Constant and choose my color [#FFFFE0FF]