You arrive in Kathmandu. Kathmandu is a UNESCO World Heritage Site, so there is much to do, and even if the many sights of cultural and spiritual significance fail to take your fancy, there is a plethora of wide-ranging markets, great bookshops and handicraft and novelty shops. See here for a complete list of things to do in KTM.
You can either fly or get a bus to Pokhara, the second-largest city in Nepal, where the vistas of the Annapurnas are spectacular. Most treks either begin in Phedi or Nayapul, both of which take between 1-2 hours to drive to from Pokhara. Assuming you start from Nayapul you will trek for 5-6 hours to Ghandruk (from Phedi you would go to Landruk). Most of the trekking is uphill through amazing forests of mixed oak, rhododendrons and terraced fields.
From Ghandruk the trail descends to a river where you cross at New Bridge. At roughly 1,600 feet you start ascending again. The trail links to another from Landruk. A brief walk, including a stone staircase, brings you to Chhomrung, a village where there is a gorgeous view of Machhapuchhre (Fish Tail) and Annapurna South. This day covers 5-6 hours of trekking and is quite undulating.
One more stone staircase takes you downwards to cross the Chhomrung Khola. You follow the west bank of the Modi Khola, passing forests of oak, bamboo and rhododendron. You then ascend to Kuldighar and make your way down a long stone staircase, ending up at the village of Bamboo where you stay for the night. A shorter day (around 4-5 hours).
You pass the remarkable limestone Hinku Caves. The path here is well-defined and undulating, with many stone steps on the way. You then follow a winding stone path before arriving at the village of Deurali where you can stay for the night. Again, another short day: 3-4 hours.
Walking for two or three strenuous hours brings you to Machhapuchhre Base Camp, a patch of dirt and rocks – a moraine, as it’s formally known – enclosed by the snow-capped peaks of Annapurnas I and III and Machapuchare. You will being dying for a break here before continuing on into the Annapurna Sanctuary. Shortly thereafter (2 hours), you find Annapurna Base Camp, the highest point of the trek (4,130m/13,545ft) where you overnight. This campsite is rudimentary and there are no showers.
Most trekkers either return to Deurali on a different route that generally winds its way downhill, or go all the way back to Bamboo. If you choose the later it will be about a 7-8 hour trek.
It is staircase time once more. This is another long one, with bamboo and rhododendron forests to either side. You go to Kuldighar and Sinuwa, then on to Modi Khola. The day ends with a sheer climb in the direction of Chhomrung, before descending to to Jhinu Danda. About 5-7 hours trekking. There are hot springs about a 20 minute walk from Jhinu Danda.
You trek through villages and terraced fields, eventually reaching Syauli Bazaar, then Nayapul. About another 6 hours trekking. From Nayapul the drive back to Pokhara takes about 1-2 hours.
The flight back to Kathmandu is spectacular, looking down on the Himalayas.