Is it possible to reserve tickets to La pedrera de la nit by telephone or internet before arriving in Barcelona ?
It's " La Pedrera de Nit".
I've never bought them via the internet although I've bought them at the "Caixa Catalunya" ATMs on the street through Telentrada. Checkout Telentrada's web site: http://www.telentrada.com You might be able to buy them.
Also make sure that it's open when you are in Barcelona because it's only open for the summer.
Unfortunately this year it was only done in July in la Pedrera so it's all over. Sorry to disappoint you.
Evening activities in Museu d'historia de la ciutat in Plaza del Rey (Roman remains) and in Monestir de Pedralbes. Look at www.museuciutat.bcn.es under activitats.