If you're planning to be in Venice before the 18th of July this year, there is an exhibition on now at the Palazzo Fortuny called La Seta e il Velluto [Silk and Velvet]. There are a number of early 20th century clothing pieces on display including a series of rare Delphos (pleated silk satin dresses) owned by American collectors.
The Palazzo Fortuny is located in the historic centre of Venice near the Rialto bridge at: San Marco 3780, Boat Stop A, S. Angelo, Route 1. The museum is open daily from 10 am to 6 pm but is closed on Tuesdays.
Mariano Fortuny was a Spanish artist who became famous in Venice in the early 20th century. Fabrics of his design are still manufactured and sold today, you can see a number of them here.
The Venice showroom is now reopened and you can go for a look (and buy fabric!) Monday to Friday, between 9:30 am and 12:30 pm and then between 2:30 pm and 5:30 pm on the Giudecca canal at no. 805.
A great book (if you can find it and afford it) is Fortuny by Anne-Marie Deschodt and Doretta Davanzo Poli. (text in English)