San Sebastian & Guided Tours. San Sebastián Esencial - OFFICIAL GUIDED TOURS ON SAN SEBASTIAN. Tourism's official tours you won't miss a single detail. Led by a professional guide, you'll discover San Sebastian's "musts", its best-kept secrets and the most curious anecdotes surrounding the city. Highlights of the route: Boulevard, Constitución square, San Vicente church, Santa María Church, Port, Town Hall, Gipuzkoa Square and Victoria Eugenia Theatre.