They had used it as their headquarters for many years.

How long had they been using this place as their headquarters?

The next thing I knew, they were using my hotel room as their headquarters.

During the 19th century the castle was used as headquarters.

The mansion was then used as headquarters of the Japanese army.

It will now be used as the Society's headquarters, a museum, and open for public tours.

We'll probably use the Rose as our headquarters, since it's set up to hold all of us.

The building was built in 1954 and 1955 by Mobil, which used it as headquarters until its move.

He owned the place and let us use it as our operational headquarters.

The first was a local farmer whose place we'd been using as headquarters for a while.