Chaflán is chamfer in English (see http://members.fortunecity.es/robertexto/archivo5/dicc_arq.h...

chamfer ['tʃæmfə]
noun
1 a narrow flat surface at the corner of a beam, post, etc., esp. one at an angle of 45°
Compare: bevel [1]
http://www.wordreference.com/definition/chamfered.htm?v=b

Here's a picture of a chamfer:

http://www.cadjapan.com/member/cad101.phtml (bottom picture in the top group of pictures)

A ref. to chamfered corners:

The square piers for the colonnades of nearly all the Missions are similar to those pictured in Plate 25 a and in Plate 22. This square piers are built of brick and plastered. At Santa Barbara, they have chamfered corners...
http://members.tripod.com/~ArtistFromHungary/colonial/coloni...

--------------------------------------------------
Note added at 2 hrs 38 mins (2004-06-28 12:46:53 GMT)
--------------------------------------------------

More refs.

The main shaft of the building is clear and simple. Hood used \"courts\" at the sides of the tower, and chamfered corners to insure that the building would always maintain an individual identity on the street no matter what might be built adjacent to it in the future.
http://users.commkey.net/daniel/amer.htm

Located in the Peninsula Hills, the building affords spectacular views of the San Francisco Bay and the San Mateo Bridge. The building\'s chamfered corners maximize the Bay views.
http://www.equityoffice.com/properties_space/building.aspx?b...