TITLE: What is the integral homology of $\mathrm{GL}_2(\mathbb{Z}[i])$?
QUESTION [6 upvotes]: I am currently trying to compute homology groups of general linear groups over the ring of integers of an imaginary quadratic number field. As I would like to check my results I would like to know if anybody knows a reference where I can find the integral homology of the $\mathrm{GL}_2$ over the Gaussian integers (or over the Eisenstein integers or some other ring of integers of an imaginary quadratic number field).
I already googled quite a lot but no useful results turned up.
Thank you for your help.

REPLY [6 votes]: There is a lot of literature on this, motivated by aplications to automorphic forms. These groups go by the name of "Bianchi groups" and that keyword should help you to find more literature on them. People who have worked extensively on this include John Cremona, Haluk Sengun, Fritz Grunewald, and Alexander Rahm. (Cremona and Sengun are colleagues of mine at Warwick.) 
Sengun recently wrote a very nice survey article "Arithmetic aspects of Bianchi groups", which you can read here: http://homepages.warwick.ac.uk/~maslao/survey.pdf.