The British Architectural Library, established alongside the institute in 1834, is now one of the three largest architectural libraries in the world and the largest in Europe. Its four million items span drawings, photographs, archives, books and models — including the world's largest collection of drawings by Andrea Palladio and a first edition of his Quattro Libri from 1570. The earliest book in the collection dates from 1478.

During World War II, when much of Europe's cultural heritage was under threat, the library stayed open and performed an unexpected act of preservation: it sheltered the archives of Modernist architect Adolf Loos, keeping them safe through the conflict. The reading room, designed by architect George Grey Wornum and his wife Miriam for the 1934 headquarters building, retains its original Art Deco interior — open bookshelves, double-height central space, original furniture. It is free to the public.

In 1934, a century after the institute's founding, RIBA moved to its permanent home at 66 Portland Place — a Grade II* listed building designed by Wornum and opened by King George V and Queen Mary. The building features sculptures by Edward Bainbridge Copnall and James Woodford on its façade. Inside, alongside the library, are exhibition galleries, a lecture theatre, a bookshop, and event spaces.

The building closed on 1 June 2025 for what has grown into an £85 million refurbishment — a figure that climbed considerably from the initial £20 million estimate announced in 2022. Staff relocated temporarily to the British Medical Association's offices in Tavistock Square while the work proceeds. The renovated building is envisioned as a new "House of Architecture" when it reopens.

The RIBA has administered some of the world's oldest architectural awards. Its President's Medals have been given annually since 1836, making them possibly the oldest architectural awards in continuous existence anywhere. The Royal Gold Medal, first awarded in 1848, honors a distinguished body of work over a career. The Stirling Prize, established more recently, recognizes the best new building of the year in the UK.

The institute also organizes architectural design competitions — a historically significant role, since it was through a competition that George Edmund Street won the commission for the Royal Courts of Justice in 1868. The RIBA's competition framework has shaped some of Britain's most significant public buildings. Its Plan of Work, first developed in 1963, remains the standard stage-by-stage process model for UK construction projects.

With 44,000 members and a London headquarters that has sometimes been perceived as the whole of the organization, RIBA has faced recurring criticism as London-centric, insufficiently transparent, and slow to reckon with its own diversity failures. In 2022, young architects organized to demand change, supporting the ultimately successful candidacy of Muyiwa Oki for the presidency. Oki became president in September 2023.

The institute's motto, in Latin, translates as "for the use of the people, for the glory of the city." It was designed by Thomas Leverton Donaldson in the 1830s and takes its imagery from the Lion Gate at Mycenae — an ancient image of power framing an entrance. Whether the institute has lived up to either half of that motto remains, as it always has been, a matter of active debate among its members.