Wing Buildings were completed in December 1977. Meanwhile, the Main Building itself finally opened on May 31, 1978. However, the rest of the intended government buildings and public spaces around the complex were never built. The legislative body first convened at the Main Building on June 12, 1978. Turned over to the House of Representatives However, under the 1987 constitution, the legislative branch again became bicameral. The numerically larger House of Representatives retained the session hall and offices of the old Batasang Pambansa on the grounds of the complex. The smaller, newly reinstated Senate returned to the original legislative building in Manila (reinstated as capital city in 1976) and held their plenary sessions there until the building was turned over to the National Museum of the Philippines under the presidency of Fidel V. Ramos. The Senate has since moved to the GSIS Building on reclaimed land on Manila Bay in Pasay, holding their plenary sessions there since May 1997. Expansion Apart from designing the core buildings of the complex, Felipe M. Mendoza and his office also allotted a master plan for possible expansion of the complex. These included: A Senate Building, containing the Senate Session Hall and Offices, on the open area at the eastern side of the Main Building The Library of Congress, Museum, and Archives on the western side of the complex Several other ancillary buildings Plans and scale models for the expansion were developed in 1978, but were not implemented. In March 2001, the Ramon V. Mitra Jr. Building was completed. Currently headquartered in the building are the Legislative Library, the Committee offices, the Reference and Research Bureau, and the Conference Rooms. The South Wing Annex Building started construction in 2008 and was inaugurated on June 29, 2010. Interior Session Hall Members of the House of Representatives hold their plenary sessions at the Session Hall, located inside the Main Building. Comprising 200+ members elected by first past the post and 50+ members elected by closed party list, the legislators debate economic, social and other issues inside the complex. The Session Hall is also used for joint sessions of the Congress of the Philippines, such as election results, confirmation meetings, and addresses by the President of the Philippines or other guests of honor. The President's annual State of the Nation Address delivered to a joint session of Congress is one example of such a speech. The Session Hall