The Dutch Physics and Astronomy laboratories and offices at Leiden University occupy a complex of 1960’s and 1970’s blocks located in a green area on the city’s periphery. The new building is linked to an existing laboratory by connecting bridges on all floors and consists of three elements: a zinc clad office block, a glazed ground floor entrance and a semi-transparent laboratory volume that intersects the office block. Tilted towards the visitor at ten degrees, the office building emphasises its prominence whilst allowing light into and views from the adjacent buildings. Horizontal strip windows provide panoramic views out of the five floors of efficiently planned office accommodation and express the cladding as a second skin. The ground floor, housing entrance, auditorium and restaurant, is executed in glass and wood and present an open atmosphere. Contrasting formally with the office block, the slightly curved laboratory building is clad in silk-printed overlapping glazing. The laboratory is located to minimise external vibrations and is designed as a pragmatic industrial hall with an internally exposed steel structure. The use of a transparent facade to the laboratories reflects the culture of instrument making, the traditional craft that first gave the university its international reputation.