Air Castle Quilt Block Tutorial – A Historic Design with Unique Piecing

Using the Light/Cream 4.5" square, and the four Medium/Blue 2.5" squares "snowball" the corners of the Light/Cream 4.5" square. I like to work on two opposite corners at a time. Click Square in a Square for a detailed tutorial on making this unit.

Here are the first steps:

• Mark a diagonal line from corner to corner on the back of the 2.5" squares. 
• Sew two Medium/Blue squares to opposite corners of the Light/Cream square along the marked line (top image). Note the orientation of the marked line.
• Match the corners of the 2.5" squares and press (bottom image).

• Open up the 2.5" squares and trim the seam allowances (top image).
• Refold (bottom image).

Step 3:

Repeat Step 2 on the remaining two corners of the Light/Cream square.

Castle Units:

Step 4:

Using the Light/Cream 5.5" square and the Medium/Yellow 5.5" square, make two Half-Square Triangle units. Press the seam allowance toward the Medium/Yellow fabric. You do not have to trim or square up these units at this time as we will trim at the end. However, if you prefer, you can trim/square up to 5". You can find my tutorial for making basic Half Square Triangles at https://fabric406.com/blogs/fabric406-blog/how-to-sew-a-basic-half-square-triangle-block

Step 5:

Mark a diagonal line perpendicular to the seam line as shown in the picture below.

Step 6:

Match up one of the Step 5 Half-Square Triangle units with one of the remaining Medium/Yellow 5" squares. The Half-Square Triangle unit will be a bit larger than the Medium/Yellow square but that's okay as you will trim this unit up in a later step. 

Step 7:

Sew 1/4" from both sides of the marked line and then cut on the marked line as shown below.

Step 8:

Open up the two units to reveal this mash up of a Half-Square Triangle and a Quarter-Square Triangle unit as shown in the picture below. Press the seam allowance toward the larger Medium/Yellow triangle. Trim/square up the units to 4.5" square.

Step 9:

Repeat Steps 5 through 8 for a total of four of these Castle units. 

Putting It All Together:

Step 10:

Lay out the Half Square Triangle units, the Castle units, and the Square in a Square unit as shown in the picture below. From here the block goes together like a basic Nine Patch block. 

Step 11:

Step 12: