Yes and the company ID.
select name,id from companies where id = ( select company_id from office_locations group by company_id order by count ( * ) desc limit 1 )
What is the building ID that has the most company offices?
select t2.id from office_locations as t1 join buildings as t2 on t1.building_id = t2.id join companies as t3 on t1.company_id = t3.id group by t1.building_id order by count ( * ) desc limit 1
What is the name of building with ID 3?
select name from buildings where id = "3"