There are a series of free concerts during Fallas, on the 14th, 15th and 16th of March, taking place in the Turia riverbed near the Serranos Towers, and in the Viveros Gardens.
Being new to Spain, I’d never heard of any of the bands, so did some research. Where available, I’ve linked to a page where you can quickly acquaint yourself with their sound:
Saturday, March 15th
Serranos, 15:00 to 21:00 – (Dance & House) Luis López, Dani Moreno, Arturo Grao, Miguel Ángel Roca, Kurd Maverick (big ups, Deutschland!)
Viveros, 21:30 – M-Clan, yet-to-be-determined support
These concerts are free, but you have to have an invitation to get it in. Where do you get these? It’s a little hard to find information, but I think that you can pick up tickets on the 4th, 5th and 6th at the following places:
Los Centros Municipales de Juventud, Radio Valencia, El Corte Inglés, Boulanger, in the Concesionario oficial Mazda de la Avenida del Puerto, Hiper Max Descuento de la Pista de Silla, and in Telepizza.
I’m pretty sure that invitations for the concerts on the 14th are available on the 4th, the 15th on the 5th and the 16th on the 6th. So, ten days in advance.
However, the tickets for the last night at the Viveros Gardens (Momo and Los Secretos) are only available in the Centros Municipales de Juventud, and the offices of “Cadena 100”, and at a date yet to be set. Because they like to make it easy.