On the space originally provided for a sidewalk on the park side of the streets and avenues, there will, in any case, be room for such a line of trees as we have proposed. The continuous exterior mall should by no means be given up, even though it cannot be made in all parts as wide as we have proposed. At many points, and frequently for quite long distances, it will form an elevated terrace, commanding extensive views over the park, of the most interesting character, and a mere parapet-wall three or four feet high, will, in such cases, be all-sufficient for the safety of promenaders and the protection of the park from interlopers. [Sidenote: Fifth avenue entrance.] The finest approach from the city is certain to be along the Fifth avenue, and it has been thought necessary to view with special care the angle of the park first reached from this direction, because it will be generally felt that immediate entrance should be had at this point.[5] [5] NOTE, 1868.—We submitted a plan for a much needed amplification in this approach during the earlier stage of the work, but the suggestion has not yet been acted on. The grade of the avenue has been established so high that considerable filling-in would be required to avoid a rapid descent, but directly this single difficulty is overcome, the ground beyond has great advantages for the purpose of a dignified entrance to the park. A massive rock that will be found in connection with this requisite made-ground, offers a sufficiently large natural object to occupy the attention, and will at once reduce the artificial feature to a position of minor importance. If, next, we stand upon that portion of the rock which (a little north of the large cherry-tree) is at grade-height, we find that there is another rocky hillock within a short distance, in the direction a visitor to the park would most naturally pursue—that is to say, towards the centre of the park. This can be easily reached by slightly raising the intermediate ground; by then sweeping to the right, the natural conformation of the surface offers an easy ascent (by the existing cart-way over Sixty-Third street) to a plateau (two rods west of the powder-house), directly connected with the extensive table-land which occupies the centre of the lower half of the park. From this plateau (now occupied mainly by the nursery) a view is had of nearly all the park up to the Reservoir, in a northerly direction; and on looking to the south and west, we perceive that there are natural approaches from these directions, which suggest that we have arrived at a suitable point of concentration for all approaches which may be made from the lower part of the city to the interior of the park. * * * * * [Sidenote: The Avenue.]