THE ASSOCIATED PRESS reports that one of the suspects of the March 11 terror arracks in Madrid was found to have a detailed skecth of Grand Central station in New York:

A suspect in the Madrid train bombings was found to possess a sketch and technical details about Grand Central Terminal in New York, U.S. officials confirmed Wednesday.

The sketch and data were on a computer disk seized about two weeks after the March 11 train bombings in Madrid that killed 191 people last year, the newspaper El Mundo said.

In New York, Mayor Michael Bloomberg said the FBI had informed the Police Department about the existence of the data on the computer and the city responded by tightening security at transit centers.

"We've known about the data on the computer for a long time," said Bloomberg, interviewed on WBLS Radio.

[...] Spanish police turned the disk over to the U.S. agents from the FBI and CIA in December once they understood the scope of the technical data, the report said.

A U.S. Embassy official confirmed that American law enforcement authorities received information related to Grand Central Terminal from Spanish authorities in December. The official declined to go into detail.

However, a Spanish police official said Spanish and U.S. authorities don't lend much credibility to the sketch, saying it is not even clear it is supposed to be a picture of Grand Central Terminal.

The police official, who spoke on condition of anonymity, confirmed the sketch was found in the home of Mouhannad Almallah, a Syrian who was arrested in Madrid on March 24 but later released, although he is still considered a suspect.

Reader Jim Uren wonders whether the nine-month period since the sketch was found until Spanish authorities passed the information to US's is due to incompetence or the desire to 'hurt' the US. I honestly don't think it's the latter; Zapatero's government might be childishly anti-American, but I don't think that up to that level. Otherwise they wouldn't have passed the tip, not even now, would they?

As for incompetence, well, it's one possible explanation, but we must base ourselves in what the newspaper that has published the information, El Mundo, reports. It's subscription only, but you can read -in Spanish- the text of that item here. The relevant quote is

Entre los objetos incautados por la policía en las operaciones efectuadas los días 24, 25 y 26 de marzo se encuentra un disquete de ordenador que incluye el dibujo de la estación neoyorkina trazado a mano. Fuentes próximas a la investigación añaden que iba acompañado de otros datos técnicos muy especializados. Por esa razón, la posible trascendencia de la información no fue valorada hasta el pasado mes de diciembre. Poco después, tras algunas consultas de tipo técnico, se decidió ponerla en conocimiento de EEUU.

In English (my translation): "A computer disk with a hand sketch of the New York station was among the objects seized by police during the operations of March 24 to 26. Sources close to the investigation add that it was together with other very specialized technical data. For that reason, the potential of the information's relevance wasn't assessed until last December. Shortly after, after several technical consultation, it was decided to pass it to the knowledge of US authorities".

So I don't know if the information was that much complicated: 9 months is an awfully long period of time to learn what that was about. Maybe they just wanted to check and re-check in order to avoid another Brandon Mayfield-like fiasco.