Masjid Aisha, terletak di the area of Taneem approximately 7 km northwest of Masjidil Haram, is the nearest Miqat point outside the Haram boundary (Hil). It is named after Aisha (may Allah be pleased with her), who was instructed by Nabi (shallallahu alaihi wa sallam) through her brother Abdur-Rahman to go to Taneem to enter Ihram for her Umrah during the Farewell Haji.
You need to go to Taneem if you are already inside Mekkah (within the Haram boundary) and wish to perform a new Umrah. Since Ihram for Umrah must be entered from outside the Haram boundary, you cannot simply make the intention from your hotel in Mekkah. Taneem/Masjid Aisha is the closest and most convenient exit point for this purpose. Other options include going to Ja'ranah or Hudaybiyah, but Taneem is by far the most popular due to proximity.
The masjid has modern facilities including: ablution areas, shalat spaces, separate sections for men and women to change into Ihram garments, and shops selling Ihram cloths and supplies. Taxis from the Haram area to Masjid Aisha are readily available — the trip takes about 15-20 minutes. Many Haji/Umrah operators arrange group transport to Taneem for those wishing to perform a second Umrah. Upon arriving at Taneem, perform mandi wajib if possible, change into Ihram, make your niyyah for Umrah, begin the Talbiyah, and return to the Haram for Tawaf and sa'i.