This fractal is called Castle. When viewed in 3D, it has an outside wall with towers along the edge.

The formula is z = 1 /( 1 / ((z + 2 + c) - 1 / (z - 2 + c))) which is similar to the formula for parallel resistors from electrical engineering. It took Fracton 25 minutes to make the model on my 8 core Mac Pro. The model has 1.5 million vertices and 2.3 million faces. The 3D image and animation were rendered in Cheetah 3D. You can view a 20 second animation of a fly through of the castle. The animation took about 1 hour to render in Cheetah 3D.

The parameter file for the fractal is:

castle { ; Exported from Fracton.
 reset=2004 type=formula formulafile=fracton.frm
 formulaname=F_20120730_1032 passes=1 float=y
 center-mag=-0.666966319204264/4.031208046200374e-1\
 0/166666.66875/1/0/0
 params=-1/1/1/1/-2/0/2/0/0/0 maxiter=2000
 inside=16 periodicity=6
 colors=pH6rH5vH3zH0vH2rG3mE2hD2cB2ZA2U81P71K51F41A\
 30510000330760BA1ED1IG1LJ1PN2SQ2WT2_W2b_3fb3ie3mh3\
 ql4tq3wu1zz0ww1tt2pp3mm5jj6gg7cc8``9YYAXVBURBROBOK\
 BLHBJDBGABD6CA3C80CC4CHH8MJ9RLBWNC`PEeSFkWInZHqaHt\
 cGwfGziFwfFtdFqaEnZEkWEhUEeREaODZMDWJDTGDQDCNBCK8C\
 413000443775BB8EFAIIDLMFPQISUKWXNZ`PbdSegUikXloZpr\
 asvcsvcsvcsvcqsaoq`mnZlkXjiWhfUfdTdaRbZP`XO_UMYRKW\
 PJUMHVKGWJGXHFYGFZEF_DEaBEbAEd9Dg9Cj8Bl8Ao89r78u77\
 r67p67n68l68i59g59e59c5A`5BZ6CW7EU8FR8GP9IMAJKBLMC\
 IOFKQHNSKPUNSWQUYSX_VZ`Y`b`cdcfffihiljlolornrulprk\
 mnikkgihffdddabbZa`W_YSYWPWUMVRITPFRNCQK8OI5RK7TN9\
 WPBYRD`TFbWHeYJg_LiaNkcPneRpgTsiVulYxn_zpawn`tk_pi\
 YmfXjdWgaVcZT`WSYURVRQROPOLOKJNHGMDDLAAKADMAGNAIPA\
 LQAOSARUBUWBXYB__CbaCecChfCkhDnjDqlDtnCqlBmjBjiAfg\
 9cf8_d8Xc6SY5NS4IM3EH29B145000311632943D54G75J87MA\
 8QB9TCAWEBZFCbHEfHBjH9nH7 }

frm:F_20120730_1032 {
 ; Similar to the parallel resistance formula
 a=real(p1),b=real(p2),d=imag(p1),f=imag(p2),
 z=0,c1=pixel-p3,c2=pixel-p4:
 z=1/(1/(a*(z^b)+c1)+1/(d*(z^f)+c2)),
 |z|<100
 }      

Export Model Settings:

Model Type: Height Field
Grid Samples X 600
Grid Samples Y 600
Min Ext Angle 10.000000
Min Edge Len 0.100000
Min Face Area 128.000000
Model Size X 10.000000
Model Size Y 5.000000
Model Size Z 10.000000
Upper Clamp 130.000000
Lower Clamp 23.000000
Texture Vert: Color Index

Model Statistics:

Total vertices: 1528802
Total faces: 2292251
Total polygons: 476
File size: 122213273
Time 24 min 46 sec on an 8 core Mac Pro