IIRC, in the past they weren’t always held physically within the Capital building. Some where held in jails in the District. Of course back then Congress ran the district. With home rule (i.e. far out leftists) in charge of DC now that wouldn’t be suitable place to hold them. Of the top of my head I see reason, other than convenience, for picking one holding cell over another. So I suggest sending off to Sheriff Joe for safekeeping. Even with the distance I bet he’d be low bid. And I’m confident he’d be willing to House Holder in his jail. They could teleconference any legal hearings from DC.
Getting them there would be the problem. The feds would intercept any prisoner transfer and take the individual and then the fight would be to recapture the person held in contempt. Again no penalty for not talking since it would take forever to get them back.
The reason congressmen would need to be used to prevent removal from the cell in the House building is it is very tough to arrest one of them due to constitutional restrictions.
In a trial your entitled to a lawyer by the constitution, but if you are being held by congress under its authority are you allowed to consult with an attorney and do the courts have any authority? The Senate won’t because it’s a desperate body and has no authority over the other except what is granted in the constitution or by the House itself. For example neither house of Congress can be in recess without the permission of the other and a member of one body can’t go on the floor of t h e other house without permission (exception is probably a former members under other rules)’