Scrap metal thieves have stolen almost 20 tonnes of girders earmarked for the new grandstand for the Edinburgh Tattoo.
Two trailers containing the girders, valued at £50,000, were taken from the Houston Industrial Estate in Livingston.
The theft happened between Sunday and Monday.
The trailers are 45ft-long red and extendable. One has the number 12 and the other 21 on a sign.
A Lothian and Borders Police spokesman said: "This theft is likely to have been planned, as specialist heavy lifting equipment would have been required to move the steel parts.
"It is possible that those responsible were mainly interested in the trailers, however we would urge members of the public to stay vigilant and to contact us if they have information.
"With steel prices remaining high, it is likely that the steel has been specifically targeted.
"It's important dealers and tradesmen are aware that this steel has been stolen, as someone may well try to sell it on in the next few days.
"It might already be en route elsewhere in the country, or might still be in the local area."