- Brand: Patek Philippe
- Made: 1971
- Model: Calatrava
- Reference: 3520
- Calibre: 175
- Movement: Manual
- Material: 18ct white gold
- Features/complications: Flat case, dial and crystal
- Dial: Silvered dial featuring black printed Roman numeral hour markers with black baton hands
- Case Dimensions: 32mm
- Bracelet/Strap: Leather strap
- Accessories: Extract from the Archives
- Web reference: 2596
Essay: The reference 3520 was launched by Patek Philippe in 1965 and at the time was classified as the ‘’flattest waterproof watch in the world’’
During its 25 years of production the reference 3520 was produced in two consecutive variants and was available in pink, yellow and white gold as well as platinum. The first series of watches were produced using a Piguet based calibre 175 until 1977 and subsequently a Geneva calibre 177 for shorter period of time.
In 1968 Patek Philippe also introduced the reference 3520D as a bracelet version of the model. The reference 3520 ceased production in 2008.