Library of Congress Happy Hour Every Thursday Visit the Library of Congress on Thursday nights for happy hour. Make sure to book your tickets in advance because they go quickly. Tickets go quickly because they are free. Events at the Library of Congress | The ... Pro tip: get your tickets individually because if you do a group order, everyone has to be there to be admitted. If someone is running late, no one can enter until they arrive. Also, bring cash because quite frequently the credit card machines are down