Construct ASCII arches
Python 2, 106 bytes (94 chars)
n=input();j=1
exec&quot;s=j/2*'║';print s+'╔'+'═'*(2*n-j)+'╗'+s;j+=2;&quot;*n
if n:t='╨'*n;print t+'─'+t

Pretty straightforward. Prints line by line with a changing number of horizontal and vertical bars. The last line is printed separately.
I feel like I'm missing some optimizations. The fact that the chars are multiple bytes means you can't do something like '║╨'[n&gt;0], so I didn't find a good way to print the last line in the loop. It's ugly that there's so much manipulation going on with the counter. I'd like update strings directly, like s+='║', but the index is also used for horizontal bars.