Washington, D.C.

The Mall is the axis everything else hangs from, and its scale is consistently underestimated: from the Capitol end to the Lincoln Memorial is a straight, largely unshaded two miles, with the memorials clustered at the far western end. Plan it as a dedicated outing rather than as something to fit around museums — ideally in the early morning or, better, after dark, when the memorials are floodlit, the temperature drops and the crowds thin. Comfortable shoes and water are not optional here in summer, and a bike-share or a circulator bus turns the long axis into a manageable one.

The Smithsonian is not one museum but a family of them, most strung along the Mall, and all free to enter. Air and space, natural history and American history draw the biggest crowds; the National Museum of African American History and Culture is widely considered the most powerful of them and may operate timed entry, so check before you go. The galleries of art sit at the eastern end. The trick is restraint: two museums in a day is a good day, four is a blur, and because entry is free you can dip in for an hour without feeling you have wasted a ticket.

The memorials are open twenty-four hours and are at their best in the evening. Lincoln's chamber is floodlit and the view back down the reflecting pool towards the obelisk is the city's defining image; the Vietnam Veterans Memorial's black granite wall and the Korean War memorial's figures are quieter and more affecting with fewer people present. The Martin Luther King Jr and Franklin D. Roosevelt memorials sit around the Tidal Basin, a pleasant fifteen-minute walk further on. A late-evening loop of these, on foot or by bike, is the single best two hours in Washington.

Step off the Mall and Washington becomes a city of distinct, walkable districts. Georgetown has brick sidewalks, federal-era houses, a canal towpath for walking or running, and the waterfront; it is the prettiest part of the city and has no metro station, so plan to walk or bus in. Capitol Hill is residential terraces and neighbourhood bars around Eastern Market. Shaw and the 14th Street corridor hold much of the current restaurant and bar scene. Mount Pleasant and Columbia Heights are the Latin American heart of the city, with the food and murals to match.

The cherry trees around the Tidal Basin are the city's most famous sight and the least reliable: peak bloom lasts only a few days, shifts by weeks from year to year with the weather, and cannot be booked in advance. If you come for it, come with the rest of the trip worth doing anyway and treat the blossom as a bonus. Autumn is the underrated season — warm days, cool evenings, colour in Rock Creek Park and far fewer people. Summer is hot and heavily humid, which is when the free air-conditioned museums earn their reputation, and winter is cold but quiet.

Most of Washington needs no reservation, but a few things do and are missed by visitors who assume otherwise. Tours of the Capitol and of certain federal buildings must be arranged in advance, sometimes well in advance and occasionally through an official channel rather than online — international visitors should check the requirements early rather than on arrival. Some Smithsonian museums use timed passes at peak periods, released on a rolling basis. Bureau of Engraving tours and the Washington Monument lift also run on limited passes. Everything else on the Mall is walk-up.

The metro is clean, safe and easy to use, and covers the Mall, Georgetown's edges, the neighbourhoods and both the closest airports; a rechargeable card or contactless payment works on metro and bus alike. Bike-share is excellent for the Mall's long axis and the Georgetown towpath. Note the airport situation, which catches people out: the closest is a short metro ride from downtown, the largest international gateway is well outside the city with its own rail link, and a third lies further north in Maryland — check which one your ticket actually uses before booking a hotel transfer.