These have since been halted in favour of concentrating public housing developments only in minor HDB towns. Over the years, the HDB began to reorganise the larger estates and amalgamate them into "HDB Towns", as has been done in Bukit Merah, Geylang and Kallang/Whampoa, while Bukit Timah and Marine Parade remained as estates. Simei, sometimes referred to as an estate and a new town, has since been amalgamated into Tampines. There are now officially 23 "HDB Towns" and three "Other Estates".