how to get old look ?

Two general methods - Washes and Pastel.

Washes - to recap quickly are thinned down paint (80/20 or more). With a building I would do a layer or two of overall wash, washing the whole thing. Use a dark first coat then lighter more brown secondary coats. Let the wash soak in as it wishes, don't worry about being 100% even. I would also add some 'spot' washes taking specific colors, maybe very dark or green for algea, or red for rust, and streak the building where water would run or the wash would be (in creases cracks and nooks).

Pastels are pigment in power form (or they get in powder form after you scrape the pastel against a #11 blade for 5 minutes). Use a larger soft brush and dip it in pastels. Then touch up and lightly brush them on the building almost in a drybrush stroke.
Use various colors in layers, and mix them too.

Dont' forget window frames.

looks old enough to me, or do you want it to look like its been shot at, if so, i use a hobby knife and flck out random pieces of the building, not to big though! just 1/35 bullet size. now, if you want a massive explosion type thing, carve out a shell hit, then put rubble in the street, cuz those shells will make rubble go everywhere

Nice building and street!!!

Debris around base of building and in gutters and street. For battle worn lots of rubble and household of business items mixed in the debris.

Paint with subdued colors - browns, tans, grays

Building - concrete, brick, stone - crack and chip with age and wear and tear. Create or paint cracks and chips. I tend to carve into the building for real cracks and chips and then wash, paint and dry brush for heighten details.

Real street/gutter dirt - That fine mixture of various sizes of dirt, pebbles and small stones that in up in the gutter make great street rubble and it is free!

Hope that helps some. Check out the many e3xceelnt articles on buildings and debris here at www.Armoramama.com . I wrote one called
Basicwall contruction - Hunter or Hunted, that might help some.
Good luck

John
www.johnneill.com

Ahhh... one of the HANSA SYSTEM kits... aren't they a ton of fun to build!? Totally unlike the plaster kits, and you can totally design whatever you like!

Look forward to seeing this unit when you are done!

building and street are hand made of plaster.
truth is that building is copy of hansa, i see picture of building on net and i like it . and build it.

Nexy...you are exellent! Props Boyo!!!
Take pastels (pencil or powder) and grind into a fine powder. Mix with a small amount of alcohol until you have a nice wash.
Here's where it's important though. Use a spongebrush to dab on the wash and then spread the dabs like your drybrushing paint.
Practice on scrap pieces of the material you used to Scratch that AWESOME CORNER!

Cuhail