Mumbai, May 6 -- Billionaire banker Uday Kotak and his family have made the country's most expensive real estate purchase, buying a flat in the 19 Shiv Sagar building at Worli Sea Face at Rs.2,74,784 per square foot. According to deal papers accessed through property portal IndexTap, the Kotaks recently bought 10 apartments of varying sizes in the building for just over Rs.224.32 crore. They had purchased 12 homes in the sea-facing building in January, with one of the apartments going at Rs.2,71,796 per sqft, a national realty record at the time. The Kotaks now own 22 of the 24 apartments in the ground-plus-two-storey building, for which they have paid Rs.426.21 crore in total. In March 2018, the Kotaks bought Champagne House, a bungalow adjacent to 19 Shiv Sagar, from Ranjit Chougule, managing director of the defunct wine firm Indage Vintners. The bungalow was purchased for Rs.275.14 crore at Rs.1.52 lakh per square foot. It is not clear whether the Kotaks will be merging the two plots. According to deal papers accessed through IndexTap, the Kotaks registered a 735-sqft flat in 19 Shiv Sagar on March 5, followed by a 2,200-sqft apartment on March 24. Seven more homes were registered on April 8, while the last purchase-of a 735-sqft flat-was formalised on April 21. One of the apartments registered on April 8 has an area of 1,004 sqft, sold by Om Prakash N Shetty for Rs.27,58,82,966. This is the most expensive realty deal in India, at Rs.2,74,784 per sqft. The per square feet price of the other nine flats vary from Rs.2,71,796 to Rs.2,73,933....