Sihleggstrasse 23, 8832 Wollerau

Switzerlands Zefix, the central index of companies (zentraler Firmenindex), is downloadable with FTP. This is of course an invitation to create a script that determines the address at which most Swiss companies are registered. Not surprisingly, this is in Wollerau, more precisly at

Sihleggstrasse 23
8832 Wollerau

At this address, 328 companies are registered!
For the reference, here's the list of the top twenty company addresses in Switzerland:

Registered companies	Street	Location
328	Sihleggstrasse 23	8832 Wollerau
304	Murbacherstrasse 37	6003 Luzern
222	Technoparkstrasse 1	8005 Zürich
203	Gewerbestrasse 5	6330 Cham
201	Baarerstrasse 75	6300 Zug
201	Chamerstrasse 172	6300 Zug
188	Neuhofstrasse 5A	6340 Baar
185	Industriestrasse 47	6300 Zug
182	Chemin du Château 26 A	2805 Soyhières
163	Riva Albertolli 1	6900 Lugano
162	Haldenstrasse 5	6340 Baar
157	Churerstrasse 35	9470 Buchs
157	Dammstrasse 19	6300 Zug
156	Rue du Rhône 100	1204 Genève
156	Weissbadstrasse 14	9050 Appenzell
149	Poststrasse 6	6300 Zug
148	Baarerstrasse 78	6300 Zug
145	Industriestrasse 21	6055 Alpnach Dorf
144	Oberneuhofstrasse 5	6340 Baar
140	Baarerstrasse 2	6300 Zug

Note how many companies are registered in Zug.